MANAMA, Bahrain » Soldiers and riot police used tear gas and armored vehicles to drive out hundreds of anti-government protesters occupying a landmark square in Bahrain’s capital, a day after emergency rule was imposed in the violence-wracked Gulf kingdom. At least four people were killed, according to witnesses and state TV.

The full-scale assault launched at daybreak swept into Pearl Square, which has been the center of uprising against Bahrain’s rulers since it began more than a month ago. Stinging clouds of tear gas filled streets and black smoke rose from the square from the protesters’ tents set ablaze.

Witnesses said at least two protesters were killed. Bahrain state TV also reported that two policemen died when they were hit by a vehicle after hundreds of anti-government protesters were driven out. The witnesses spoke on condition of anonymity because of fears of reprisals from officials.

It was unclear whether the offensive included soldiers from other Gulf nations who were dispatched to help Bahrain’s Sunni monarchy, which has been under relentless pressure from the country’s majority Shiite Muslims to give up its monopoly on power.

But state TV broadcast video showing military vehicles in the square flying Bahrain’s red-and-white flag as security officials moved through the wreckage of the encampment, set up at the base of a towering monument to the country’s history as a pearl diving center. The video showed the ground littered with debris, including satellite dishes and charred tent poles.