Updated

A British military helicopter crashed in Basra on Saturday, and Iraqis hurled stones at British troops and set fire to three armored vehicles that rushed to the scene. Clashes broke out between British troops and Shiite militias, police and witnesses said.

Police Capt. Mushtaq Khazim said the helicopter was apparently shot down in a residential district. He said the four-member crew was killed, but British officials would say only that there were "casualties."

CountryWatch: Iraq

British forces backed by armored vehicles rushed to the area but were met by a hail of stones from the crowd of at least 250 people, who jumped for joy and raised their fists as a plume of thick smoke rose into the air from the crash site.

The crowd set three British armored vehicles on fire, apparently with gasoline bombs and a rocket-propelled grenade, but the soldiers inside escaped unhurt, witnesses said.

British troops shot into the air trying to disperse the crowd, then shooting broke out between the British and Iraqi militiamen, Khazim said. At least four people, including a child, were killed and 31 wounded, he said. Two of the fatalities were adults shot by British troops while driving a car in the area, Khazim said.

The crowd chanted "we are all soldiers of al-Sayed," a reference to radical Shiite cleric Muqtada al-Sadr , an ardent foe of the presence of foreign troops in Iraq.

Later the crowd scattered after hearing explosion, but groups of men set fire to tires in the streets and the situation remained tense. The chaotic scene was widely shown on Iraqi state television and on the Al-Jazeera satellite station.

The attack on the helicopter came at a difficult time for the government of Prime Minister Tony Blair in Britain, where many people oppose the U.S.-led Iraq war.

After a poor showing by his Labour Party in local elections this week, Blair overhauled his Cabinet, ousting Foreign Secretary Jack Straw following rumors that he and Blair had differed on issues including Iraq. Straw reportedly had expressed doubts about the Iraq war to his boss.

In violence elsewhere, a homicide bomber wearing an Iraqi army uniform entered an Iraqi base in Tikrit and detonated an explosives belt, killing an Iraqi lieutenant colonel, a major and a lieutenant and wounding a lieutenant colonel, said the Iraqi Defense Ministry spokesman, Maj. Gen. Abdul-Aziz Mohammed Jassim.

The U.S. command also announced that an American soldier was killed by the roadside bomb in Baghdad on Friday. At least 2,417 members of the U.S. military have died since the Iraq war started in March 2003.

Britain has about 8,000 soldiers based in the mostly Shiite Basra area. Southern Iraq has long been much less violent than Baghdad and western Iraq where Sunni Arab-led insurgents and al-Qaida in Iraq launch many attacks against Iraqi civilians and U.S. and Iraqi forces.

But Grand Ayatollah Ali al-Sistani, the Shiite religious leader, hasn't always been able to keep growing anti-coalition fervor among Shiite radicals under control.

In September, British forces arrested two officials of the Mahdi Army, the Shiite militia loyal to al-Sadr, raising tensions in Basra. About a week later, militiamen and residents clashed with British troops after two soldiers disguised as Arabs were detained by Iraqi authorities.

British forces launched a raid to free the men and an Iraqi judge issued a homicide warrant for their arrest. British officials said the warrant was illegal under Iraqi law and their personnel were immune to prosecution in Iraq.

The bomber in Saddam Hussein's hometown of Tikrit targeted a group of Iraqi army recruits who had just finished their training and were being dispatched to another area of Iraq, Jassim said. Officials in Tikrit said the bomber apparently told guards that he wanted to see one of the officers and was admitted to the base without being searched.

The attack in the Sunni Arab city 80 miles north of Baghdad appeared to be part of a campaign by Sunni-led insurgents to discourage Sunnis from joining Iraqi security forces. The Bush administration hopes that newly trained Iraqi soldiers and police can one day improve security in Iraq enough to begin withdrawing U.S. forces from the country.

In a bid to counter the U.S. efforts, Sunni militants have targeted Sunnis who cooperate with the government, including Iraqi army and police.

A roadside bomb also exploded Saturday near a Polish convoy in Diwaniyah south of Baghdad, wounding three soldiers, Poland's Defense Ministry said. Poland has about 900 soldiers in south-central Iraq, where it commands an international force.

In other developments Saturday:

• Fighting between an Iraqi military patrol and insurgents killed two soldiers and three militants in Youssifiyah, 12 miles south of Baghdad.

• A bomb in a parked car exploded, killing two policemen and an Iraqi soldier and wounding four civilians about 30 miles north of Baqouba, police said.

• Suspected insurgents kidnapped seven Iraqis, including three paramilitary policemen, south of Baghdad in an area where a roadside bomb killed three U.S. service members the day before.

• Roadside bombs hit two Iraqi police patrols in Baghdad, killing one officer and wounding two policemen and six civilians.

• Two rockets or mortar shells were fired in northern Baghdad, one hitting a home and killing two children and wounding a woman.

• Police in Baghdad found the bodies of 13 Iraqi men, five of them relatives from Iraq's Sunni Arab minority, who had been kidnapped and brutally killed, police said.

• A drive-by shooting killed two brothers in Baghdad, police Capt. Firas Queti said.

• A roadside bomb in the northern city of Mosul wounded two Iraqi policemen. Police also found the bullet-ridden bodies of a father and son who had been kidnapped earlier in the day.

• Iraqi and U.S. forces searched shops for weapons and imposed a curfew in Rawah, a Sunni city 175 miles northwest of Baghdad.