Officials in Bahrain say street battles between police and pro-democracy activists Tuesday killed at least two people and wounded hundreds of others.
The violence comes as the government declared a state of emergency to try to end the uprising.
Medical officials say police killed one man in the town of Sitra, while the government says a member of the security forces was run over and killed by a protester driving a car in another area.
Hospital workers say hundreds of other people were wounded in fighting around the country, some by gunfire.
Bahraini state television said Tuesday King Hamad bin Isa al-Khalifa ordered the commander of the armed forces to take "appropriate measures" to safeguard the nation against protesters whom he accused of "terrorizing" the population.
The king gave permission Monday for about 1,000 Saudi soldiers and 500 United Arab Emirates police to protect Bahraini government buildings.
Thousands of protesters marched outside the Saudi embassy in Manama, calling the military presence an "occupation."
In Cairo, U.S. Secretary of State Hillary Clinton said she telephoned Saudi Foreign Minister Prince Saud al-Faisal to urge him to push for a dialogue in Bahrain. Clinton said a credible political settlement is the only durable solution.
Protesters from Bahrain's majority Shi'ite population have been demanding political reforms from the minority Sunni government.
The ruling al-Khalifa family has offered to hold a dialogue with opposition groups. But some protesters are demanding more power for parliament and that the royal family be ousted.
The streets of the Bahraini capital's financial district were deserted Tuesday, with many stores closed and major highways blocked by police and barricades set up by opposition activists two days earlier. The barricades have stopped business activity in Manama, a regional banking hub.
The U.S. State Department is warning Americans against travel to Bahrain and advising citizens in the Gulf state to consider leaving.
In Washington, White House spokesman Jay Carney called on Gulf nations to show restraint in Bahrain, but said the United States does not consider the deployments of Gulf troops as an invasion. He also did not call for the withdrawal of the Saudi and UAE forces.
Oil-rich Bahrain is home to the U.S. Navy's Fifth Fleet, which provides support to U.S. troops in Iraq and Afghanistan.
Some information for this report was provided by AP, AFP and Reuters.