Police in Northern Ireland say two 17-year-olds and a 16-year-old have died after a crowd of revelers trying to get into a St. Patrick's Day event caused what appears to be a crush.

A 16-year-old girl remains hospitalized after the incident at the Greenvale Hotel in Cookstown on Sunday evening.

Assistant Chief Constable Mark Hamilton said Monday that it appears the crowd was pushing toward the door to get into a disco event. "People then seem to have fallen and then got crushed."

He says police "need people to come forward and tell us what happened last night. Three young people are dead, they deserve a full inquiry."

Police appealed to witnesses not to share images on social media, but to give the material to authorities.