A massive manhunt is underway after one person was shot to death and four others were injured at a Zombie-themed festival in the US state of Florida.

The shootings began at 11:45 p.m. Saturday during ZombiCon, an annual event in its ninth year, which was expected to have drawn more than 20,000 people.

Police were looking for a suspect early on Sunday.

The four people who were hurt were taken to Lee Memorial Hospital for treatment. They did not have life threatening injuries, police said.

Lt. Victor Medico of the Fort Myers Police Department said there were “a lot of witnesses” taking pictures and videos with their cell-phones, adding that “anything that could help with this investigation would be greatly appreciated.”

The investigation was ongoing and the circumstances of the shootings remained unclear.

Police officers with rifles patrolled the streets around the crime scene and ordered people to clear the area.

Detectives were also canvassing the area in search of witnesses.

Over 10,000 people have been killed and over 21,000 people have been injured by guns in the United States since January 1, 2015, according to the Gun Violence Archive.