Ninety-six balloons are released as You'll Never Walk Alone echoes around Anfield.
Today's service at Anfield finishes with the release of one balloon for each of the victims of the Hillsborough disaster.
Victims' families commended the club for supporting them and for the words of manager Brendan Rogers and Everton manager Roberto Martinez.
Margaret Aspinall, the chair of the families' support group thanked the clubs and managers for their support and introduced a rendition of the Liverpool anthem.
Supporters gathered outside Anfield before today's service.
Thousands watch on as families of the 96 victims take their places at Anfield for the service.
As fans, relatives and survivors gather at Anfield to pay their respects to those killed in the Hillsborough disaster 25 years ago, similar memorials have taken place at the Sheffield Wednesday stadium.
The stadium's own memorial has had flowers, flags and scarves laid at it throughout the day as people remember the 96 people who died there in 1989.
Services are being held this afternoon in Sheffield and Liverpool to mark 25 years since the Hillsborough disaster.
A minute's silence will be held in Liverpool for the 96 fans who died.
David Hirst reports.
The focus of the memorial service for the 96 victims of the Hillsborough disaster will be at Anfield today.
People have been congregating at the stadium to pay their respects to those fans who went to see their team play but did not come home.
Stuart Littlewood survived the tragedy in 1989 and has since moved to live in Australia. He sold his scooter and car to pay for his flights back to be at Anfield today.
Fans from across the country have been laying flowers and hanging scarves on the walls and gates on Anfield Road.
There will be a memorial service later today and a city wide two minutes silence at six minutes past three.
Thousands of people will attend memorials this afternoon to commemorate the anniversary of the Hillsborough tragedy.
The services will take place at Anfield Stadium, home ground of the 96 people who died, and at HIllsborough.
At the weekend Sheffield Wednesday paid tribute to the victims by placing personalised roses on 96 seats ahead of their match with Blackburn.
The city of Liverpool will come to a standstill today as it remembers the 96 lives lost in the Hillsborough disaster 25 years ago.Read the full story ›
The jury in the inquest to the Hillsborough tragedy is to make a visit to the stadium - but should not read the "deeply moving" tributes.Read the full story ›
It said in a statement Scotland Yard said:
_ "We have been asked in recent days whether undercover officers were deployed into the Hillsborough campaign._
"We replied that we will neither confirm nor deny details of the deployment of undercover officers. This is a long-established practice to avoid criminals targeted for undercover operations drawing conclusions if we were to give negative answers in some cases but not comment in others.
"Once we start denying false or incorrect allegations, our silence in other cases could be taken as a confirmation, and that could be very damaging and dangerous for those who risk their lives to combat organised and serious criminality.
"The 'neither confirm nor deny' policy is a practice we also follow in the courts when asked whether an individual was an informant or an undercover officer, and judges have accepted its legitimacy in the interests of the wider public good.
"It may look strange in an era of greater transparency and accountability, but we believe this principle continues to protect those who take the greatest risks on all our behalf."
"We would like to explain that the reason why under the Freedom of Information Act, we could not provide an answer, was to protect national security and undercover police tactics. The language used was relevant to those issues and was not a comment upon any of the Hillsborough Groups.
"We note that no-one has drawn to our attention any evidence that has been published to suggest that undercover officers were deployed over Hillsborough."
Scotland Yard will remain silent over claims that undercover officers spied on Hillsborough campaigners "to protect national security and undercover police tactics", the force has said.
It refused a Freedom of Information request by the magazine Private Eye for files on the Hillsborough Justice Campaign and the Hillsborough Family Support Group amid claims the campaigners were put under surveillance.
The force has a policy to neither confirm nor deny what police moles have been up to, in a bid to protect officers who work undercover.
Scotland Yard said the Private Eye request was refused to protect tactics.
The "neither confirm nor deny" approach prompted anger among bereaved parents trying to discover whether their dead children's names had been used by undercover officers.
Last summer Jules Carey, solicitor for Barbara Shaw who believes that her son Rod Richardson's name was used, said she felt her complaint to Scotland Yard had been "swept under the carpet".
A report found that the names of 42 dead children were used by officers trying to create watertight false identities.