Witnesses said heavy clashes broke out in Karma after insurgents attacked a US military convoy using mortars, rocket-propelled grenades and automatic weapons.
They said at least two US military vehicles had been damaged and troops had cordoned off the area, but it was not clear whether there were any American casualties. The US military had no immediate comment.
Ahmed Ghani, a doctor at Falluja's main hospital, said 11 Iraqis had been killed and more than 20 wounded. A call was put out for locals to donate blood to help the wounded.
Ten people were killed and 37 wounded when a suicide car bomb and roadside bomb targeting local officials exploded simultaneously in Mosul, police, US military and medical sources said.
"A car bomb and a roadside bomb exploded as Major-General Sammi al-Haj Issa's nine-car convoy passed by," said police Brigadier General Adnan Obeidi in Mosul.
Issa, who is chief of the city's security committee, was slightly wounded by the blasts which struck the convoy as it passed the city hall and a school in central Mosul, said Obeidi.
Issa's son Akram was also wounded, the general said, adding that the car was parked when it detonated.
The US-led coalition said the convoy, that included two members of Ninevah provincial council and Mosul's deputy chief of police, was the target.
"The council members were not wounded. The deputy chief was wounded, but not seriously," it said in a statement.
The explosion damaged nearby buildings but left the municipal building unscathed, the coalition added.
The city morgue reported four killed, while another six were recorded dead at al-Salam hospital, according to Dr Hissam Abdul Karrem al-Jabbar.
Mosul's four hospitals put the final number of wounded at 37.
The US military said the car bomb exploded at 9:15am.
"Witnesses said the car bomb was an orange and white taxi; witnesses saw three suicide bombers in the car," the military said in its statement.
A suspected car bomb killed four Iraqis and an American soldier outside the main US military base in the northern Iraqi town of Baquba on Tuesday, police and a US military spokeswoman said.
The explosion wounded three US troops, said the spokeswoman.
Police officer Ali Hussein said 11 Iraqis were wounded. He said the attack may have been a suicide car bombing.
A wounded Iraqi, who was standing in line to go work at the US base, said he saw a man in a traditional flowing white robe drive towards the compound at high speed just before the blast.
At least six soldiers serving with Polish-led forces in Iraq were killed and several more wounded in a blast on Tuesday during a demining operation, officials said.
Those killed in the explosion at Suwayrah, south of Baghdad, included three Slovakian, two Polish nationals and a Latvian, officials from the three countries said.
"The incident took place during a demining operation," said Polish military spokesman Colonel Zdzislaw Gnatowski. "The accident happened in an old munitions depot dating back to the Saddam Hussein era."
According to Czech news wire CTK, the explosion happened in a Polish army vehicle, which was carrying unexploded ammunition to be destroyed.
A US Marine was killed in the restive al-Anbar province west of Baghdad on Monday, the US military said in a statement on Tuesday.
The statement said the soldier, assigned to the First Marine Expeditionary Force, was killed while conducting "security and stability operations" in the province, which includes the cities of Falluja and Ramadi.
Special forces from the US-led coalition in Iraq raided a hideout south of Baghdad on Tuesday and freed three Italian hostages held for almost two months and a Pole abducted last week, Italian officials said.
The three Italians were in good condition and were expected to return to Italy on Wednesday.
"This was a happy ending to a story that could have been tragic," Italian Prime Minister Silvio Berlusconi said on state television.
Berlusconi said the men were being flown by helicopter to Baghdad and were due to return to Italy on Wednesday.
His government had more than one reason to be happy.
Berlusconi said forces had identified the location where the hostages had been held several days ago and had considered approaching local religious authorities to help win their freedom.
But the forces took advantage of a window of opportunity on Tuesday and launched an operation to free them. He gave no details on the operation.
The Pole freed along with the Italians on Tuesday was Jerzy Kos, a manager with Polish construction company Jedynka.