Manama, Bahrain (CNN) -- Security forces in Bahrain stormed the main hospital, beating doctors, and attacked demonstrators in Manama's Pearl Roundabout on Wednesday, witnesses in the Bahraini capital said. Bahraini officials deny these accounts.
Demonstrators reported hearing steady rounds of ammunition being fired while thick smoke rose from the Pearl Roundabout area. At least five helicopters whirred above the historic landmark, which has been a rallying spot for anti-government demonstrators in recent weeks.
In a statement Wednesday, Bahrain's government said that as police approached the roundabout, they were attacked by protesters -- whom they call "saboteurs" -- who threw Molotov cocktails at them. Police dispersed the protesters with tear gas, as protesters set fire to tents and trash cans on their way out, the government said.
According to the government, no live ammunition was used, and the only fatalities were two police officers who were repeatedly run over by three vehicles driven by protesters. Three arrests were made, an interior ministry spokesman said.
The crackdown comes a day after Bahrain's King Hamad imposed a three-month state of emergency and two days after Saudi Arabia and the United Arab Emirates dispatched troops to the Persian Gulf island nation to "protect the safety of citizens," the Bahraini government said.
The clashes prompted Iran to recall its ambassador to Bahrain in what an Iranian government statement called a protest against "the killing of people of Bahrain by their government."
Bahrain's Sunni Muslim monarchy has long suspected Iran of attempting to foment unrest among the island's majority-Shiite population, leaked U.S. diplomatic documents show, and Iran has asserted territorial claims over the onetime Persian province both before and after the 1979 revolution brought the current Islamic republic to power
Speaking in the Egyptian capital of Cairo, U.S. Secretary of State Hillary Clinton called the intervention by Bahrain's neighbors "alarming" and urged all players in the region to keep "their own agenda" out of the struggle. Washington has told the Bahraini monarchy that "there is no answer to the demands for political and economic reform though a security crackdown," Clinton told CNN's Wolf Blitzer.
And President Barack Obama called both the Saudi and Bahraini kings to express his "deep concern over violence" and the need for "maximum restraint," according to White House spokesman Jay Carney. Bahrain is home to the headquarters of the U.S. Navy's Fifth Fleet, the naval arm of American power in the region.
Cell phone networks in several areas were disrupted. Security forces blocked highways leading to the capital and formed a ring around the country's main hospital, Salmaniya Medical Complex, not letting people enter or leave, witnesses said.
Security forces then stormed the hospital and beat staffers, several doctors there said.
Doctors have been hiding in rooms, said Yousif Sharaf, a doctor at the hospital.
"We are trapped," Sharaf said. "We are asking for the security forces to please stay outside the hospital. They are beating the staff."
Fatima Haji, another doctor, also said she was trapped in the hospital.
"We are in a small group hiding," Haji said, her voice rising with emotion. "This is a government hospital. How can this happen in a government hospital?"
Haji said two people had died in the hospital Wednesday morning, and she feared for the other patients there because the doctors were not able to work.
Eventually, the army told hospital workers that they could leave, but they had to give their names and have their pictures taken, Haji said. Some of her colleagues were taken to the gates and beaten, she said.
CNN could not independently confirm the doctors' claims.
The Bahraini government expelled CNN's Mohammed Jamjoom from the country Wednesday without explanation. Reporting from Abu Dhabi, United Arab Emirates Jamjoom said two Bahraini information ministers came to his hotel and told him that the rest of the CNN crew was welcome to stay, but he was not.
"I was then escorted to the airport and made to leave the country," Jamjoom said.
Jamjoom said he and others were woken by the sound of gunfire Wednesday morning.
"We could see thick black plumes of smoke. We could see tear gas being dispersed," Jamjoom said. "It was a very, very violent scene from where we were looking on it."
Calls made to various hospitals turned up multiple accounts of witnesses being attacked, including medical staff and doctors, Jamjoom said.
On state-run television, a banner read, "Official source: Media allegations that medical care is being denied to patients are baseless."
Dr. Nazar Al Baharna, Bahrain's minister of health, resigned later in the day. He did not elaborate on the reason why.
Officials at another private hospital, Salmany Hospital, also said they were being besieged by troops.
It was unclear whether the attacks were carried out solely by Bahraini forces or included foreign troops who arrived in the country earlier in the week to help quell the demonstrations.
The Bahraini government denied the allegations and said foreign troops had been dispatched to secure specific installations, not participate in the crackdown.
A curfew was in effect from 4 p.m. Wednesday to 4 a.m. Thursday in various parts of the capital, the foreign ministry said.
Meanwhile, the U.K. Foreign Office announced Wednesday that the British Embassy in Bahrain was closed until further notice.
A day earlier, security forces fired tear gas and rubber bullets at protesters in the southern city of Sitra.
At least two protesters were killed, and at least 150 people were wounded, according to medical officials on the scene.
The protests started February 14 and are part of a series of demonstrations that have swept across the Arab world this year, toppling the leaders of Tunisia and Egypt.
In Bahrain, moderates have been demanding a constitutional monarchy, and hard-liners have called for the abolition of the countries' royal family altogether.
The king's decree mandates that security forces should "take the measures and procedures necessary to preserve the safety of the nation and its people," a government statement said.
"King Hamad's decree does not give the authorities a blank check to commit abuses," Joe Stork, deputy Middle East director at Human Rights Watch, said Wednesday. "The world is watching to see whether Bahrain will respect the basic rights of all its citizens."
CNN's Mohammed Jamjoom and Lateef Mungin contributed to this report.