Gunmen on motorcycles have killed 41 people in a bus in the Pakistani city of Karachi, police say.
Police said six attackers boarded the bus and opened fire on the passengers, who were from the Ismaili community, a minority Muslim sect in majority-Sunni Pakistan.
Local television pictures showed a pink bus covered in bullet holes.
"There were six attackers. They boarded the bus and carried out the shooting," police superintendent Najib Khan told Reuters.
No group has immediately claimed responsibility for the attack.
A military helicopter carrying foreign diplomats has crashed today, killing the ambassadors of Norway and the Philippines, as well as the wives of the ambassadors of Malaysia and Indonesia.
Two Pakistani pilots were also killed in the crash, according to Military spokesman Asim Bajwa.
Update Naltar:2 pilots,4 foreigners fatalities.(Ambs Philippine, Norway,wives of Malaysian& Indonesian Ambs).Injured-Polish&Dutch Ambs-5
Pakistan's Prime Minister Nawaz Sharif was also travelling to the northern region of Gilgit in a separate aircraft when the accident happened. He returned to Islamabad when he got the news.
In total 11 foreigners and six Pakistanis were on board the MI-17, which crashed into a school. The ambassadors of Poland and the Netherlands were injured.
Pakistan are set for a return to hosting Test-playing nations after Zimbabwe confirmed a tour will take place in May.
No full Test member of the International Cricket Council has toured Pakistan since 2009, when a terrorist attack on the Sri Lanka team bus left six policemen and two civilians dead, with several players injured.
'Home' games for the 1992 World Cup winners have since been played in the United Arab Emirates, but things have slowly been looking up, with Afghanistan and Kenya undertaking tours to Pakistan over the last year or so.
And Zimbabwe will now be the first full Test nation to set foot in Pakistan, in a series comprising two Twenty20 internationals and three one-day internationals for late May.
In press conference statements published via their official Twitter feed, Zimbabwe cricket managing director Alistair Campbell said: "We are touring Pakistan as a measure of establishing bilateral relations between us and them.
"They will also come to Zimbabwe in August."
An anti-terrorism court in Pakistan has sentenced 10 men to 25 years in prison for the 2012 shooting of Malala Yousafzai.
Ms Yousafzai, who was awarded the Nobel Peace prize in 2014 for her campaign for women's and children's rights, was shot in the head on her school bus in Swat when she was just 15.
Authorities say that the 10 men are all members of the Pakistani Taliban, though none of them were among the four or five men who actually carried out the attack.
"Judge Mohammad Amin Kundi in his verdict gave 25 years jail to all of these people," said a court official in Swat, which is in the northwest of the country.
Malala remains unable to return to Pakistan, due to Taliban threats on her and her family's lives.
Two hostages, an Italian and an American, were killed in a US counter-terror operation at an Al Qaeda compound near the border of Afghanistan and Pakistan in January, the White House has said.
The White House expressed sorrow over the deaths of American Dr Warren Weinstein and Italian Giovanni Lo Porto and said it previously had no reason to believe any hostages were at the building targeted.
In a statement, the White House added that an Ahmed Farouq, an American Al Qaeda leader, was also killed in the operation, while another US member of the militant group, Adam Gadahn, was killed in January.
Barack Obama is set to make a statement at 3pm BST
Pakistan all-rounder Mohammad Hafeez is free to resume bowling in international cricket after remedial work and a re-test on his action.
Off-spinner Hafeez, 34, was banned from bowling after being reported for a suspect action five months ago in the first Test against New Zealand in Abu Dhabi and then failing an initial test on its legality.
He was therefore unable to be selected to bowl in the World Cup, but injured his calf anyway and was ruled out of the global tournament in Australia and New Zealand.
Hafeez played as a specialist batsman in Pakistan's one-day international defeat against Bangladesh on Sunday, making a duck at number three in the defeat in Dhaka.
But after the International Cricket Council confirmed his action has been proven legal in Chennai this month, Hafeez can bowl again for his country.
Javeria Khan, an all-rounder in Pakistan's women's team, has also had her action cleared - almost five years after it was first reported and then failed an initial ICC test.
Pakistan appear set to host Test-playing opposition in their home country for the first time in more than six years.
Zimbabwe have reportedly agreed to travel for a short one-day international series next month, likely to take place in Lahore and Karachi.
No tourists have played in Pakistan because of security fears since the terrorist attack on Sri Lanka's team bus in Lahore in March 2009 - when six policemen and two civilians died, and several of the tourists were injured.
'Home' Test and ODI series' in the meantime have taken place in the United Arab Emirates, England's destination for the second time this autumn, a tour for which an exact schedule is still to be confirmed.
The details of Zimbabwe's proposed trip are also not yet known.
But Pakistan Cricket Board president Shaharyar Khan has stated that, after discussions with his Zimbabwean opposite number Wilson Manase, he expects the short tour to go ahead.
He (Manase) told me they are coming and they are coming with their full team - but (just) for a week.
They will send a security team to assess the situation, following which they will confirm the tour. So they will come in the middle of May, and our efforts will be to host matches in Lahore and Karachi.
The West Indies answered their critics as they battered Pakistan on both sides of the ball to get their World Cup campaign up and running with a 150-run victory in Christchurch.
Denesh Ramdin and Lendl Simmons laid the foundations for the Windies, with knocks of 51 and 50 respectively, before Andre Russell sparkled with an unbeaten 42 off just 13 balls to guide them to 310 for six.
With four wickets gone and 10 overs remaining the Windies cut loose, piling on 115 runs from their final 60 balls, although they were helped by poor Pakistan fielding throughout at Hagley Oval.
The White House said that President Obama welcomed improved relations between Pakistan and Afghanistan. US officials also expressed an appreciation for Pakistan's efforts to combat terrorism.
Officials in Pakistan are rushing to restore power after a massive blackout hit the country earlier this morning.
Up to 80% of Pakistan was without power, but by mid-morning power had been restored to about half of the country.
A militant attack in the southwestern Baluchistan province caused the blackout, according to Zafaryab Khan, a spokesperson for the Ministry of Water and Power.