At least four people are feared dead in a shooting on the closing night of the BPM Festival in Mexico.
Shots were reported at the popular Blue Parrot club in Playa Del Carmen, Cancun.
Four to five people were reportedly killed after a gunman fired through an open window of the club.
Jackmaster, a Scottish DJ playing at the festival, tweeted to say someone came into the club and opened fire, killing four to five people and injuring many others.
He said festival goers should stay in their hotel rooms.
A second shooting is believed to have happened at The Jungle club.
George de Menezes told The Independent: “We were in the Blue Parrot nightclub and literally two metres from us shots started going off.
"No one took it seriously, but I knew straight away that it was a gun and dropped to the floor, then everyone dropped with me.
"The music stopped and so did the shots, so we got up and one man was down on the floor and looked dead, and another man had been shot but was trying to stay on his feet."
He added: “Everyone tried to run out to the beach from the club and all of a sudden we heard another shot and everyone dropped again and it kept going on.
“Finally got out from there and got up to the Main Street and there was another man dead on the street, so everyone started running for their lives."
He said he heard more shots after getting back to his hotel, along with reports of shootings at other clubs.
“We don’t know if it’s a terrorist attack or something else, but we were the first ones to hit the ground and watched it all unfold.
"If he’d turned on us, we’d probably be dead.”
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."
The festival has been running for 10 years and is popular with foreign tourists, especially from the UK and US.
Local media reports claim the shootings are cartel-related, however authorities are yet to comment.
