Frenzied clashes swept Bahrain Tuesday, a day after a Saudi-led military force entered the country to defend its Sunni monarchy from a Shia-led protest movement. Hundreds of demonstrators were injured by shotgun blasts and clubs, a doctor said.

As the government's crackdown intensified, the Bahraini king declared a three-month state of emergency Tuesday that gave his military chief wide authority to battle protesters demanding political reforms and equal rights for Shias. One demonstrator was shot in the head and killed, and a Saudi official said one of his country's soldiers was shot dead by a protester.

The force of more than 1,000 Saudi-led troops from several Gulf nations saw its first day of action to help prop up the U.S.-backed regime in Bahrain. Its intervention was the first major cross-border military action to challenge one of the revolts sweeping across the Arab world.

Further underlining the regional implications of the unrest in Bahrain, Shia power Iran denounced the foreign intervention as "unacceptable" and predicted it would complicate the kingdom's political crisis.

Iran holds no deep political ties to Bahrain's Shia groups, but some Iranian hard-liners have hailed their efforts over the years for greater rights for their community, which represents a majority of the nation's population.

The United States bases its Navy's 5th Fleet in the country in part to try to counter Iran's military reach.

Saudis should promote dialogue: Clinton

Secretary of State Hillary Rodham Clinton says she has prodded Saudi Arabia to support a peaceful reform process in Bahrain amid increasing U.S. concerns about sectarian violence in the country.

Anti-government protesters shouts slogans near the Saudi Embassy in Manama on Tuesday, as Bahrain's king declared martial law to quell an uprising by the island's Shia Muslim majority. Hamad I Mohammed/Reuters

Clinton said she spoke with Saudi Foreign Minister Prince Saudi on Tuesday and stressed that "they along with everyone else need to be promoting the dialogue" between Bahrain's Sunni monarchy and a Shia-led protest movement.

Speaking in Cairo, Clinton said reports of provocations and sectarian violence risked worsening the situation in Bahrain. She said the sides "must take steps now to negotiate toward a political solution."

Gulf leaders have urged Bahrain's king not to give ground, fearing that gains by Bahrain's Shia Muslims could offer a window for Iran to expand its influence on the Arab side of the Gulf.

There are also worries that political concessions could embolden more protests against their own regimes, which have already confronted pro-reform cries in Oman, Kuwait and Saudi Arabia.

'We are expecting they will attack us any minute now'

Tuesday's worst confrontations took place on the Bahraini island of Sitra.

A 24-year-old protester, Ahmed Farhan, was shot in the head and killed, said Dr. Ibrahim Youssef, a member of the medical team at the Sitra Health Center. Youssef said hundreds of others were injured by shotgun blasts and clubs.

"Hundreds of people are here. They are everywhere — in the halls, on the floor of the health center," he said. "People are screaming. There is lots of blood."

There was a growing conviction among the protesters, centered in the tent camp in the capital's Pearl Square, that the monarchy is unwilling to meet their demands for an elected government and a voice for Shiites in running the nation.

"They brought tanks from Saudi Arabia and other Gulf states to keep the monarchy as it is, not to change it," said Ali Issa, a protester manning a checkpoint on a road leading to the square.

"We are expecting they will attack us any minute now."

'We have no guns, but we will resist by remaining here as long as we possibly can.'—Protester Ali Hassan

At the square, thousands of protesters were still in shock over the arrival of the neighboring armies when the state of emergency was declared.

"We are ready for anything, but this protest started peacefully and it will end peacefully," said Ali Hassan, a demonstrator in Pearl Square. "We have no guns, but we will resist by remaining here as long as we possibly can."

The emergency law statement said the head of Bahrain's armed forces has ordered authorities "to take necessary steps to restore national security."

Senior opposition leader Abdul Jalil Khalil said the monarchy's steps indicated it has decided to "give a military solution to a political problem."

"They want to talk with a gun on our head, and saying, you either take this or you die," said Khalil, a leader of Bahrain's main Shiite group, Al-Wefaq.

A security official in Saudi Arabia said a Saudi sergeant was shot and killed by a protester in Bahrain's capital, Manama. No other details were immediately given on the death of the soldier, identified as Sgt. Ahmed al-Raddadi.

Throughout the unrest, protesters have displayed no weapons and have adopted the chant of "peaceful" as a main slogan. The Saudi official spoke on condition of anonymity because he was not authorized to talk to the media.

Protests began last month

Shia account for 70 percent of the population, but are widely excluded from high-level political or security posts. The protesters also demand the repeal of a government policy to offset the Shia demographic advantage by giving citizenship and jobs to Sunnis from other Arab nations and South Asia.

The protests began last month with calls for the monarchy to give up most of its powers to the elected parliament. But as violence has deepened, many protesters now say they want to topple the entire royal family.

The foreign troops are from the six-nation Gulf Cooperation Council's Peninsula Shield Force. The bloc is made up of Saudi Arabia, Oman, Kuwait, Bahrain, Qatar and the United Arab Emirates.

Saudi Arabia and the UAE have announced roles in the Bahrain force, but the contributions from the other countries were not immediately clear.

The U.S. was informed of the foreign troop intervention a day before the deployment, said Defense Department spokesman Col. Dave Lapan.

"We have communicated to all parties our concerns regarding actions that could be provocative or inflame sectarian tensions," Lapan said.

He said the commander of the Navy's 5th Fleet will decide whether to send military personnel or family members out of the country. A 5th Fleet spokesman did not immediately respond to a telephone query about what is planned.