Eighteen U.S. troops and five Iraqi government soldiers have been killed in action since the start of the assault on Fallujah (search), the U.S. commander of the operation said Thursday.

Maj. Gen. Richard Natonski, commander of the 1st Marine Division, also said 69 American service members and 34 Iraqi troops had been wounded since the assault began Monday against insurgents in the Sunni Muslim stronghold.

Natonski said the operation was "ahead of schedule" and he saluted "the soldiers, sailors, airmen and Marines and our Iraq comrades" taking part in the fight.

"Today our forces are conducting deliberate clearing operations within the city, going house to house, building to building looking for arms caches," he said.

Natonski also said he had visited a "slaughter house" in the northern Jolan (search) neighborhood where hostages were held and possibly killed by militants.

He described a small room with no windows and just one door. Inside were two thin mattresses, straw mats covered in blood, he said.

There was also a computer, computer disks, and a wheelchair where "we believe (captives) were bound and moved around in."

He said intelligence personnel are investigating the site.

The presence of the "slaughter house" was first disclosed Wednesday by the Iraqi commander, Maj. Gen. Abdul Qader Mohammed Jassem Mohan.