ZAMBOANGA CITY, Philippines: President Gloria Macapagal Arroyo imposed martial law on Maguindanao on Saturday and authorities arrested the patriarch of a powerful political clan linked to the brutal slaying of 57 people in the southern province.

The president was accused of overreacting by invoking emergency powers in response to the country’s worst incident of political violence. It was the first time martial law has been declared in the country since the late dictator Ferdinand Marcos imposed it more than three decades ago.

Aside from Andal Ampatuan Sr. a former governor of Maguindanao, police and military also arrested several clan members. They included the patriarch’s sons — the governor of the Muslim autonomous region, Zaldy Ampatuan, and his brothers Akmad Ampatuan, the deputy provincial governor, and the mayor of Shariff Aguak town, Anwar Ampatuan. They are being questioned about the Nov. 23 mass murders.

The elder Ampatuan was brought to hospital in Davao City due to hypertension and would be in the custody of the military’s Eastern Mindanao Command.

At a news conference in Manila on Saturday, Executive Secretary Eduardo Ermita said martial law would allow authorities to arrest without warrants all those implicated in the killings.

But he was quick to say that areas identified as strongholds of the Moro Islamic Liberation Front, which is negotiating peace with Manila, would be out of the purview of martial law. Justice Secretary Agnes Devanadera said some members of the Ampatuan clan are considered suspects in the murders of 57 people, among them at least 30 journalists and the rest supporters and family members of Esmael Mangudadatu, the deputy mayor of Buluan town who is a candidate for governor in Maguindanao in next year’s elections.

The family has denied involvement.

The chief suspect in the massacre, Andal Ampatuan Jr., the mayor of Datu Unsay town, surrendered three days after the murders and denied involvement in the attack and pointed the finger at the Moro Islamic Liberation Front. Authorities rejected the allegations, saying witnesses identified him as the leader of the group that abducted and massacred the 57 people.

The Ampatuans, notorious for running a large private army, have previously been allied with Arroyo, who received crucial votes from the volatile southern region during 2004 elections. Arroyo’s ruling party expelled the clan after the massacre.

Under the post-Marcos constitution, Arroyo can enforce martial law for 60 days, unless Congress revokes or extends it.

Former President Fidel Ramos, who was a supporter of Arroyo but has recently been critical of her actions, described her move as “overkill.”

In Saturday’s announcement, Ermita cited military reports as saying heavily armed supporters of the Ampatuans had “plans to undertake hostile action” if clan members were arrested.

— With input from agencies