Eight people have been killed and several others seriously injured in attacks in Somalia's capital.
There have been several mortar attacks this year
A mortar has landed on a Koranic school, killing a female student, following a series of overnight attacks on camps housing Ethiopian soldiers.
A BBC correspondent in Mogadishu says the violence seems to be worsening. It is not clear who is responsible.
Meanwhile, Islamist leader Sheik Sharif Sheik Ahmed has told the BBC he wants talks with the interim government.
He said he would take part in negotiations in Somalia if the political climate was right.
The BBC's Mohammed Olad in Mogadishu says dozens of female students began shouting and crying after the shell landed on the roof of their school, killing a student and wounding seven others.
Sheikh Soon Salad Ilmi, director of Mogadishu's Madina hospital, where the wounded were taken, said some had life-threatening injuries.
Deputy Defence Minister Salad Ali Jelle blamed "the hardline remnants" of the Union of Islamic Courts (UIC) for the escalating violence but insisted that his interim government was in control.
Mr Ahmed is seen as a moderate
"We have suspects and we know the areas where they plan their attacks," he said. "We will punish them."
Government troops had sealed off the entire area close to the main port and the Mogadishu airport after the overnight attacks.
Four people including a woman and two children were killed in Mogadishu's southern Barakat district, reports the AFP news agency.
"The woman and children were killed by a stray mortar which destroyed their house," relative Amina Asheyr told AFP.
Mr Ahmed told the BBC's Somali Service that he was in constant contact with the rest of the UIC leadership, both inside Somalia and abroad.
He was speaking from Kenya, where he surrendered to the authorities after the Islamists were driven from Mogadishu.
Some Ethiopians have started to leave Somalia
Mr Ahmed is seen as a moderate and the US, the UN and the EU have all urged the Somali government to hold talks with him.
Mogadishu has seen a rise of violence this year since the transitional government forces and their Ethiopian backers defeated the UIC who had controlled the city and large parts of southern Somalia.
Government officials say there are more than 3,000 Islamic fighters in Mogadishu.
Ethiopia is seeking an early withdrawal from the country despite slow progress in drumming up an African peace keeping force.
Uganda, Nigeria, Ghana and Burundi are the only countries to have publicly offered to contribute to the proposed 8,000-strong force.