Baghdad, Apr 26 (VOI) – A joint force of Iraqi and U.S. troops, backed by military choppers, stormed on early Thursday the Shiite Sadr city in eastern Baghdad and made some arrests in the city, local residents said.

"Joint force of Iraqi and U.S. forces stormed in early Thursday neighborhoods in Sadr city," an eyewitness told the independent news agency Voices of Iraq (VOI).

"U.S. choppers dropped a number of bombs on these neighborhoods," he added.

Another eyewitness said "the forces started a wide-scale arrest campaign and ended with the arrest of several civilians."

"The crackdown operations last till this morning," a third eyewitness said. No word was available on the number of the captives from U.S. army and Iraqi authorities.

Located in the eastern area of Baghdad, Sadr city is the largest city in Baghdad with a population of 2.5 million. It is the stronghold of the Muqtada al-Sadr’s followers and of the Mahdi Army.

US forces announced the killing of three gunmen in Sadr City on Thursday, "during an operation in Sadr City targeting a network that trains terrorists for operations in Iraq," in a statement released Thursday.

"Four armed terrorists engaged Coalition Forces with small arms fire, and Coalition Forces exercised proper self-defense measures, killing one," the statement read.

"A vehicle approached Coalition Forces during the engagement, which occurred during curfew hours. Vehicle movement is not allowed during curfew, and Coalition Forces disabled the vehicle. The vehicle caught fire and the two occupants ran into a nearby building."

"Four more armed terrorists entered the area and hid behind a stationary vehicle while they engaged Coalition Forces with small arms fire. Coalition Forces returned fire with automatic weapons, killing two terrorists and destroying the vehicle," the statement continued.