A spate of gunfire and mortar attacks in the Somali capital killed five people overnight and injured at least four others, witnesses said Friday.

An Associated Press reporter saw five bodies in open areas of the city with gunshots to their chests. The motive for the killings was not clear.

Four mortar attacks overnight injured four people, including a 3-year-old girl, said businessman Mohamed Bad Mushani, who was nearby when the shells hit.

Police Commissioner Ali Mohamed Hassan Loyan told the AP the attackers were "hell-bent on undermining the security of the country. The police will track them down."

Somalia has been increasing security this week as Ethiopian troops, whose military strength was crucial to helping Somalia's government drive out a radical Islamic militia, begin withdrawing from the country. It was not clear when the withdrawal would be complete.

Many Somalis resented the Ethiopian presence; their countries fought a war in 1977. But without Ethiopia's tanks and fighter jets, the Somali government could barely assert control outside one town and couldn't enter the capital, Mogadishu, which was ruled by the Council of Islamic Courts. The U.S. has accused the group of having ties to Al Qaeda.

On Thursday, gunmen attacked Ethiopian soldiers at a busy market in the southern Somali town of Kismayo, killing one and wounding another and sending screaming residents fleeing the area, witnesses said. Forty people were arrested.

Kismayo, the third-largest city in Somalia, was the last major town held by the Union of Islamic Courts before the Somali government and Ethiopian forces took over.

The withdrawal of Ethiopia, which says it cannot afford to stay in Somalia, raises a sense of urgency for the arrival of a proposed African peacekeeping force. The African Union has approved a plan to send about 8,000 peacekeepers for a six-month mission that would eventually be taken over by the U.N.

Nigeria, Malawi and Uganda have said they want to contribute troops, but no firm plans are in place.

Earlier this month, Ethiopian and U.S. forces were pursuing three top Al Qaeda suspects but failed to capture or kill them in an AC-130 strike in the southern part of Somalia. A main target that time was Fazul Abdullah Mohammed, one of three senior Al Qaeda members blamed for the 1998 bombings of the U.S. embassies in Kenya and Tanzania.

The U.S. Navy also has had forces in waters off the Somali coast, where they have monitored maritime traffic, boarded suspicious ships and interrogated crews in an attempt to catch anyone escaping the Somalia military operations.