At least five people have been killed and another 15 people wounded at a nightclub in the Playa del Carmen resort after a "lone gunman" opened fire during a music festival, officials in Mexico have said.
It comes after witnesses reported seeing shots fired at the Blue Parrot club in Playa del Carmen on the closing night of the BPM music festival.
The victims included two Canadians, an Italian and a Colombian - three of whom are believed to have been part of the security detail at the 10-day event.
According to officials the lone gunman apparently entered the nightclub and began to exchange fire with another person, causing a rush of people heading for the exits.
Glasgow DJ Jackmaster tweeted: "Someone has come into the club in Playa Del Carmen and opened fire. 4-5 dead and many wounded. Stay in ur f***** hotel if you're here at BPM."
He later added on Twitter: "This is a very very sad situation. Tryna get my head around it still. Thoughts and condolences to all affected."
Others posted videos on Twitter of people fleeing from the Blue Parrot.
The government of the Caribbean coast state of Quintana Roo, where Playa del Carmen is located, confirmed four men were shot to death and one woman died in a fall during the confusion that ensued after the gunman started shooting.
According to officials four people have been detained, but it is unclear if the shooter is one of them.
There were also unofficial reports of a shooting at another venue called The Jungle.
A spokesman for the Foreign Office said: "We are seeking information from emergency services in Mexico, following reports of a shooting in Playa del Carmen."