Did 21 teenagers die due to gas leak in South African nightclub?

South African authorities were seeking answers on Monday, a day after 21 underage teenagers partying after the end of school exams died in a mysterious incident at a nightclub.

The bodies of many of the victims, the youngest a 13-year-old girl, were discovered by police lying on tables, slumped in chairs and couches, and sprawled on the dance floor of the club in the early hours of Sunday morning.

Speculation has swirled over the cause of the tragedy, starting with a stampede - that has now been ruled out - with a gas leak a possibility.

Police have sent forensic samples from the victims to a toxicology laboratory to investigate if the teens ingested poison or a toxin at the party.

Police said they were called to the Enyobeni Tavern in the city of East London in Eastern Cape province in the early hours of Sunday morning after receiving a report that there were "lifeless bodies" there.

Officers responding to the call walked in on a grim scene: 17 of the teenagers were found dead in the nightclub. Two more died at a local clinic, one died on the way to another hospital and one at that hospital.

Their ages were between 13 and 17, police said.

Police spokeswoman Col. Athlenda Mathe said an investigation was ongoing and no cause of death had yet been established.

The teenagers were reportedly celebrating the end of mid-year exams, a local DJ's birthday and the relaxing of some of the last COVID-19 restrictions in South Africa, which was announced earlier in the week.

Also watch: 21 teenagers found dead in South African nightclub

Parents were asked to come to a mortuary to identify their children.

The Eastern Cape health department said there were survivors being treated in the hospital for backache, tight chests, vomiting and headaches.

It's illegal for anyone under 18 to consume or buy alcohol in South Africa and the Eastern Cape Liquor Board said it was revoking the nightclub's liquor license and would pursue criminal charges against the club's license holder.

The tragedy will put renewed scrutiny on the many bars and nightclubs operating in the backstreets of poor neighborhoods in South Africa and which are often criticized for not abiding by liquor laws.