Four children were found unresponsive on a beach in Quebec Saturday morning and later pronounced dead after a group of people on a fishing trip got caught in the tide, police said.

A spokesperson for the Quebec provincial police told CNN that emergency responders were called at 2 a.m. on Saturday to Portneuf-sur-Mer, a riverside municipality on the northern shore.

Eleven people went missing after leaving by foot for a fishing trip and being caught by the tide, the spokesperson said. Six of those 11 people were rescued, and five remained missing overnight, he said.

Around 6 a.m., four children, all over the age of 10, were found unresponsive and sent to the hospital, according to the spokesperson. Police later confirmed that the children were dead.

A man in his 30s is still missing, according to Quebec provincial police, and a search for him with divers, boats, and helicopters is ongoing.

Quebec provincial police are investigating the circumstances of the incident, the spokesperson said.