UPDATE | 2 reported dead in New Year's attack on Istanbul nightclub

ISTANBUL (AP) — An assailant believed to have been dressed in a Santa Claus costume opened fire at a nightclub in Istanbul during New Year's celebrations, killing at least two people and wounding several others, Turkish media reports said.

Private NTV television said a police officer and a civilian were killed in the attack targeting the popular Reina nightclub in Istanbul's Ortakoy district.

Media reports said more than one assailant may have been involved in the attack and more than 500 people were inside the club at the time.

The attacker is believed to have opened fire at police outside the nightclub before entering and firing on people inside. Some customers jumped into the waters of the Bosporus to escape the attack, the report said.

NTV television said the assailant may still be inside the nightclub.

Footage from the scene showed at least six ambulances with flashing lights and civilians being escorted out. NTV said police had cordoned off the area and an operation to capture the assailant was ongoing.

An AP photographer says police cordoned off the area about 2 miles (3 kilometers) away from the nightclub and reported multiple ambulances passing by.