ISTANBUL (AP) — Istanbul’s governor says at least 35 people were killed in the attack at a nightclub in Istanbul during New Year’s celebrations.

Vasip Sahin said some 40 other people were wounded in the assault in the early hours of Sunday.

Sahin said the incident was a “terror attack” without saying who may have carried it out.

Security measures had been heightened in major Turkish cities, with police barring traffic leading up to key squares in Istanbul and the capital, Ankara. In Istanbul, 17,000 police officers were put on duty, some camouflaged as Santa Claus or street vendors.

Ankara and Istanbul have been targeted by several attacks in 2016 carried out by the Islamic State group or Kurdish rebels, killing more than 180 people.

The assailant is believed to have been dressed in a Santa Claus costume. 35 people dead, 40 wounded. Update w/@foxnewsradio at 8p.m. https://t.co/Cg4iBgKFzb

— News/Talk 95.3 MNC (@953MNC) January 1, 2017