Scottish DJ Jackmaster issued a warning to clubbers after a gunman opened fire on the closing night of the BPM music festival in Mexico.
A statement from festival organisers said a lone shooter opened fire at the Blue Parrot nightclub in Playa Del Carmen.
Four people are believed to have been pronounced dead - including BPM security staff - and at least another 12 people were injured.
Eye-witnesses William Rogers explained how he was outside The Blue Parrot when shooting broke out and ran with other revellers into nearby Mandala nightclub to take cover.
He said: "I was in the 12 North street of Playa Del Carmen almost in front of Blue Parrot.
"I was 50 meters of the place when we heard several shots.
I entered to a nightclub called Mandala to cover from shots.
Once there they closed doors quick and told us to cover.
"The shooting lasted for a few seconds and we were in Mandala for around 30 to 45 minutes until the Mexican police, military and ambulances had arrived and security allowed us to leave."
Fellow DJ and eye-witness James Chapman told DJ Mag: “I heard upwards of 10 or 20 shots that sounded like fire crackers.
"Everyone stopped to see what was going on and I just saw people looking in one direction on the dance floor.
Then there were screams and everyone just ran.
“I was in the booth and everyone there ran out the back. We ended up in a hotel lobby. There we started walking and someone screamed so we ran again."
DJ Jackmaster - real name Jack Revill - had previously been Tweeting about how well the festival had been going, until shortly after 8am (UK time) this morning.
His first message read: "Someone has come into the club in Playa Del Carmen and opened fire. 4-5 dead and many wounded. Stay in ur f**kin hotel if you're here at BPM."
Around 15 minutes later he added: "Apparently now more shots fired at another club in the area."
The BPM festival features several venues hosting parties and events on the closing night of the festival, which featured over 150 of the world's top DJs, producers and acts.
FeA statement from BPM said: "It is with great sadness to share that police have confirmed reports of a lone shooter outside the Blue Parrot nightclub in Playa Del Carmen earlier today, which resulted in four fatalities and twelve injured.
"The violence began on 12th street in front of the club and three members of the BPM security team were among those whose lives were lost while trying to protect patrons inside the venue.
The BPM Festival has been working closely with the local authorities (Seguridad Publica / Policia Turistica) throughout the festival to ensure public safety and security for all visitors.
"We are overcome with grief over this senseless act of violence and we are cooperating fully with local law enforcement and government officials as they continue their investigation.
Our thoughts and prayers are with all the victims and their families and all those affected by these tragic events.