Somali Islamist group al Shabaab on Saturday shelled residential areas in the town of Baidoa, west of the capital Mogadishu, hitting a hospital and likely causing casualties, the African Union (AU) peace keeping force AMISOM said in a Twitter post.

The al Qaeda-allied group, which wants to topple Somalia's Western-backed government and rule the country according to Islamic Sharia law, has been ramping up attacks on both civilian and military targets in recent months.
"Al Shabaab militants fired mortar shells at densely populated civilian residential areas in Baidoa town this morning," AMISOM said on its Twitter account.
"One round of the mortars hit a hospital. Civilian casualties are unknown but expected."
Security analysts have warned that the group could step up attacks, taking advantage of the distraction caused by campaigning for a presidential election due in August.
The group has also launched attacks in Kenya and Uganda which have contributed troops to the 22,000-strong AMISOM force.
In the most recent attacks, al Shabaab late last month used vehicle-borne suicide bombers to launch assaults on an AMISOM base and the headquarters of Police's Criminal Investigations Directorate (CID) both in Mogadishu.
The attacks left at least 23 people dead.
Somalia has been gripped by violence and lawlessness since early 1990s following the toppling of military dictator Mohamed Siad Barre.