Thai commandos today launched a predawn raid on a sprawling provincial hospital west of here and retook it from members of a Burmese rebel group--whose leaders are preteen twins--who had seized the facility along with its patients and staff on Monday.

Automatic weapons fire crackled and large explosions could be heard as Thai soldiers raced inside the compound in trucks and jeeps in the assault.

Afterward, Thai authorities announced that nine rebels had been killed and several Thai soldiers and police officers were injured, while one of the Burmese rebels escaped and was being pursued. None of the hundreds of terrified patients, hospital staff members and visitors who had been held hostage was injured, officials said.

The assault in Ratchaburi, about 75 miles west of Bangkok, came 22 hours into the dramatic takeover. The crisis began Monday when the rebels, wearing face masks and wielding automatic weapons and grenades, burst into the facility demanding treatment for their wounded comrades and an end to Thai involvement in their obscure insurgency on the Burmese border.

The rebels involved in the seizure are said to be members of a rebel group called God's Army, a small Christian breakaway faction of a larger guerrilla force of Burma's ethnic Karen minority. God's Army is led by gun-toting, cigarette-smoking 12-year-old twins, Johnny and Luther Htoo, whose 200-odd followers are said to believe the boys possess mystical powers. It was not known whether the pair participated in the takeover.

The rebels had apparently placed explosives around the hospital and had threatened to blow it up, along with the hostages, if their demands were not met.

The Thai assault came after a day of negotiations that saw about 50 hostages freed, mostly in exchange for food. But at nightfall Monday, the rebels were still holding at least 700 people. Thailand was under intense pressure to take a tough stand against the rebels following a similar hostage-taking incident less than four months ago, in which another Burmese dissident group seized Burma's Bangkok embassy. That seizure ended when the student-rebels were allowed to escape.

The God's Army rebels who seized the Ratchaburi hospital were demanding that Thailand send medical teams to treat their wounded comrades at their mountain base in Burma, and allow the guerrillas to take refuge on Thai territory from a Burmese military advance. The rebels also demanded that Thailand stop its shelling of the border in support of the Burmese military operation. Thailand met some of the rebel demands.

Little is known about God's Army, except that it is a breakaway faction of the main Karen guerrilla group called the Karen National Union. The Karen National Union has been fighting the Burmese government for 50 years on behalf of the ethnic Karen people seeking a homeland. Karens comprise about 7 percent of Burma's population.

As the negotiations progressed during the day, Thai Interior Minister Sanan Kachornprasart, who was directing the talks from Bangkok, hinted that an assault might be imminent, saying, "I do not expect the negotiations to be protracted."

Thai media reported that commandos had infiltrated the facility disguised as medical personnel and provided intelligence on the situation to the gathering strike force.

A Thai television cameraman was allowed inside the building Monday, and his footage, broadcast on television here, showed scores of frightened hostages huddled on benches, while rebels brandishing automatic weapons paced around them.

Last October, five Burmese students from a group called the Vigorous Burmese Student Warriors seized Burma's Bangkok embassy, taking scores of hostages, including diplomats and tourists. That 25-hour crisis ended under a deal in which the student-rebels were taken to the border and allowed to disappear into the jungle.

Those young hostage-takers, who said they were fighting for democracy against Burma's brutal ruling junta, were known to have taken sanctuary at the border with God's Army, the group responsible for Monday's hospital takeover.

The military dictatorship in Burma--which calls the country Myanmar--severely criticized the October deal that essentially allowed the hostage-takers to go free.

The members of God's Army are mostly Christian in the overwhelmingly Buddhist country (about 30 percent of Karens are Christians). The 12-year-old twin leaders have been filmed in the past smoking and aiming assault rifles. Several very young soldiers also appeared among the ranks.

The rebels who seized the hospital Monday had apparently stormed across the border and hijacked a bus, where they forced the driver to make the 45-mile drive to Ratchaburi. They burst into the hospital compound firing their weapons.

It was unknown whether any of the Vigorous Burmese Student Warriors were among the God's Army guerrillas at the hospital.

The rebels at first herded all the doctors and nurses into the emergency room, but later allowed them to tend to patients. One nurse, who spoke on a mobile phone to Thai television, said she hid in one room with the door locked and the patients lying on the floor. "It's very tense," she said.

The Thai army commander, Gen. Surayud Chulanond, said Thai shelling of the border area would be halted. The military also agreed to admit unarmed rebels for medical treatment in Thailand.

CAPTION: 12-year-old Johnny Htoo, left, and his twin brother Luther are leaders of the Burmese insurgent group that raided a Thai hospital Monday.