Kurdish fighter in Mosul Kurdish fighters have moved into fill the vacuum in the north A US commander has admitted that American troops did shoot and kill a number of Iraqis during a protest in the northern city of Mosul. Brigadier-General Vince Brooks said US marines and special forces soldiers fired at demonstrators on Tuesday after they came under attack from people shooting guns and throwing rocks. "Fire was indeed delivered from coalition forces, it was lethal fire and some Iraqis were killed as a result, we think the number is in the order of seven and we think there were some wounded as well," he said. A BBC correspondent in the city says Mosul is extremely tense - and latest reports from there say at least three people have been killed and several others wounded by gunfire. The French news agency quotes an Iraqi police officer as saying the police fired into the air to disperse looters who were trying to rob a bank. Eyewitnesses said US troops then fired on a crowd close to the building from nearby rooftops. Conflicting claims US forces had earlier denied responsibility for the killings on Tuesday. Witnesses said US troops fired into a crowd growing increasingly hostile to a speech being given by the town's newly appointed governor. A US spokesman said troops were returning fire from a nearby building and did not aim into the crowd. The incident underlines the difficulties US forces face in trying to keep the peace in a country now confronting an uncertain future. Some reports suggest up to 15 people were killed in Mosul, with between 60 and 100 people injured. The trouble began as an angry crowd gathered outside the governor's building, demanding that Kurdish peshmerga fighters and Americans leave the city, witnesses told the BBC. US soldier (R) in Kirkuk The US military has a major security problem The city's population is dominated by Sunni Arabs fiercely opposed to Kurdish control. Mosul's new governor, Mashaan al-Juburi - an Arab associated with the peshmerga - appears to have tried to pacify the crowd. "He said everything would be restored, water, electricity, and that the Americans [were democratic]," Marwan Mohammed told AFP. "The Americans [troops] were turning around the crowd. The people moved toward the government building, the children threw stones, the Americans started firing. Then they prevented the people from recovering the bodies," he said. But this account was contradicted by another witness who told the BBC the first shooting sounded like it came from a light weapon - "a Kalashnikov, not like the weapons Americans have". Kirkuk reprisals Details are also emerging of revenge attacks which apparently took place in the days following the withdrawal of Iraqi troops from Kirkuk, also in the north of the country. The human rights organisation, Human Rights Watch, which has just been on a four-day visit to the city, says Baath party officials were the targets of reprisal killings. At least 40 people died in such attacks, the organisation says. "They got caught out in clashes between [the withdrawing Iraqi government] and mainly armed civilians," said Hania Mufti, a member of the delegation visiting the city. "Some of them died in these clashes. Others were wounded, but then they were dragged out and shot dead." The organisation has also expressed concern over the plight of about 2,000 Arabs who say they were forced to leave their villages around Kirkuk. They were settled there in the 1970s as part of the Iraqi Government's campaign to "Arabise" an area which had previously belonged to Kurds. Massoud Barzani, leader of the Kurdistan Democratic Party, has condemned any attacks on Arabs by Kurds, and appealed for all Iraqi "brothers" to "safeguard the spirit of peaceful and fraternal coexistence".