U.S. forces continue to conduct airstrikes against the Iraqi city of Fallujah, hitting a suspected militant hideout. The fighting comes as Iraqi human rights workers condemn the abduction of two Italian aid workers Tuesday from their central Baghdad office.

Witnesses say explosions from U.S. airstrikes first rocked the city of Fallujah before dawn and continued throughout the day. U.S. officials say the target was a building militants used to coordinate attacks against U.S. troops.

It is the second day of air strikes against the city, a stronghold of resistance to the U.S. presence in Iraq. On Tuesday, officials said they went on the offensive against militants after an attack on a routine U.S. patrol. A day earlier, a car bomb killed seven U.S. soldiers.

Street fighting has also flared in the Baghdad neighborhood of Sadr City, where both Iraqi and U.S. officials have failed in their efforts to broker a peace deal with militants that would allow reconstruction aid to get through.

Meanwhile, human rights workers in Baghdad have issued an appeal for the release of two Italian aid workers kidnapped from their office Tuesday. Gunmen broke into the office of the non-governmental organization, Bridges to Baghdad, and seized Italians Simona Pari and Simona Torretta along with two Iraqis.

Rights workers say the families of scores of Iraqi children helped by Bridges to Baghdad are also calling for the safe release of all four aid workers.

"They have brought with them for Iraq, love, treatment, help and they are trying to make a healthy society in Iraq," said Hannah Adwar, with the al Amel Association. "During the sanction time we always remembered the tremendous work [that] has been done by this organization. So we are appealing to all people to these kidnappers that please do not hurt our friends, [the] Simonas."

Other rights workers have condemned the abduction as a crime against Islam. More than 100 foreigners have been kidnapped in Iraq, often by groups who want to pressure their governments into leaving the country.

Two French journalists, kidnapped nearly three-weeks ago, remain missing.