BAGHDAD (AP) — An Iraqi security official says 18 people have been killed and hundreds wounded in an attack against protesters in Iraq's Shiite holy city of Karbala.

The official says the attack happened early on Tuesday, as Iraqis took to the streets for a fifth consecutive day, protesting their government's corruption, lack of services and other grievances.

An eyewitness says dozens of protesters were in a tent encampment they had erected in a city square when live bullets were fired toward the protesters from a passing car.

The witness says masked gunmen in black plainclothes arrived then and started shooting at the protesters. He spoke on condition of anonymity, fearing for his safety.

Karbala, as other cities in Iraq's predominantly southern region, has been gripped by a wave of deadly anti-government protests.