Kenya's military says its warships have shelled the port of Kismayo in Somalia, the largest town still held by al-Shabab militants.

Witnesses told VOA that two warships began firing at Kismayo overnight Tuesday. The attack continued after sunrise, with one shell hitting a house and wounding a child.

Kenyan military spokesman Cyrus Oguna told VOA the warships opened fire after being attacked by al-Shabab fighters on shore. Oguna said this is the first time Kenya's military has engaged in combat in Kismayo.

Al-Shabab fired on the vessels with 106-millimeter recoilless rifles.

The fighting opened a new battle line against the al-Qaida-allied group. Last week, African Union and Somali forces began pushing al-Shabab militants out of another stronghold — the Afgoye corridor located west of Mogadishu.

AU and Somali forces say they have successfully moved the rebels out of the corridor, which includes sprawling camps for about 400,000 internally displaced Somalis.

Military officials said al-Shabab was preventing aid groups from operating in the area.

Reports from southern Somalia on Monday indicated that al-Shabab leaders were mobilizing fighters in Kismayo and other locations.

Al-Shabab is fighting to overthrow Somalia's transitional government and impose a strict form of Islamic law.