The Gulf island kingdom of Bahrain was in turmoil on Thursday night after police cracked down brutally on protests in the capital, killing at least three people in a hail of tear gas, buckshot and rubber bullets.

A major rift opened up with Bahrain's Western allies as Hillary Clinton, the U.S. secretary of state, led calls for an explanation and assurances that there would be no repeat.

The police raid took in the middle of the night, when protesters who had vowed to occupy Manama's Pearl Square until their demands for a democratically elected government were met, were asleep. Police surrounded the square and moved in with tear gas and rubber bullets.

"They were beating me so hard I could no longer see," said Dr Sadek Al-Ikri, 44, who was in a medical tent when it was stormed by police. "There was so much blood running from my head. I was yelling, 'I'm a doctor, I'm a doctor,' but they didn't stop."

The number of dead, injured and arrested was disputed. The health ministry said three people had been confirmed dead and 195 injured, one critically. Protesters alleged there were organized efforts to hinder treatment of the injured.

"This is an atrocity," said Abdul Jalil Khalil, leader of the opposition al-Wefaq Party. "Whoever took the decision to attack the protest was aiming to kill."

The party represents the Shia majority of Bahrain, which has long sought a bigger part in the government, dominated by the Sunni al-Khalifa royal family. Al-Wefaq announced on Thursday that it was pulling out of parliament and demanded the government's resignation.

Later in the day, more protesters gathered outside the al-Sulmaniya Hospital, where many of the injured had been taken. They beat their chests, chanting "death to the al-Khalifa".

General Tarek al-Hassan, the interior minister, issued a statement defending the use of force against the protesters.

"The security forces evacuated Pearl Square after having exhausted all chance of dialogue," he said. "Some left the place of their own accord, while others refused to submit to the law, which required an intervention to disperse them."

By the afternoon, Pearl Square had been cleared of all evidence of the protesters, while tanks and armoured vehicles had flooded the city centre to prevent any recurrence.

Bahrain is a key ally of the United States and home to the U.S. Fifth Fleet. Nevertheless, the U.S. reacted strongly to the violence. "We call on restraint from the government and to keep its commitment to hold accountable those who have utilised excessive force against peaceful demonstrators," said Mrs Clinton.

The U.S. is also concerned at events in Yemen, where police once again fired on protesters on Thursday, killing one man in the southern city of Aden.

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