MANILA, Philippines, March 5 (UPI) -- Filipino police have arrested several men for questioning about at least two explosions that rocked southern towns in the Philippines Tuesday, killing an American and at least 26 others and injuring more than 100.
President Gloria Macapagal-Arroyo has called an emergency Cabinet meeting on internal security and sent senior officials in her government to oversee handling of the bombings on the island of Mindanao.
Arroyo also said several men have been arrested and are being interrogated for information about the attacks.
The first and more deadly explosion occurred around 5:20 p.m. local time Tuesday at Davao City International Airport, the result of what police believe was a knapsack bomb. About 40 minutes later, a grenade exploded in Davao del Norte, an hour's drive from Davao City, said Chief Superintendent Vidal Querol of the Philippine National Police. Another explosion reportedly took place at a bus terminal in Ecoland, killing two in addition to the three others, the Manila Bulletin reported.
It was the latest in a wave of violence that has hit the island since fighting resumed between the Filipino military and Muslim rebels, and the second time a Mindanao airport has been attacked in as many weeks.
"I heard a tremendous explosion, then I saw people sprawling on the ground," said taxi driver Bobby Cabanban, according to the Philippines Daily Inquirer's Web site.
Eyewitnesses described a man who walked into the airport's crowded waiting area, set down a bag and walked back out shortly afterwards. The explosion occurred a few minutes later.
"It was just seconds after I sent off my wife when I heard a very loud explosion. I rushed back and saw people lying in the waiting shed, including a baby," said a Philippines Airlines supervisor, Ephraim Fernandez.
Also among the victims at the airport were four Americans. "We understand that the bomb ... killed at least 27 persons and injured at least 140 more," U.S. State Department spokeswoman Tara Rigler told United Press International in Washington. "We also have confirmation that one of the dead is an American citizen, and three others injured are American citizens." The State Department is withholding their identities until families are notified, she added.
No information was yet available about the other victims, who authorities have said include both foreigners and Filipinos.
No one has yet claimed responsibility for the attacks nor have authorities released what they believe may have been a motivation. Arroyo called the airport bombing "a brazen act of terrorism that will not go unpunished."
The Moro Islamic Liberation Front -- the country's biggest separatist group, and the Muslim militants blamed for a car bombing at another Mindanao airport on Feb. 20 -- denied any involvement and offered to help find the perpetrators. MILF spokesman Eid Kabulu, speaking on local radio, said it was continuing attacks on the Filipino military but that its policy was not to target civilians.
"We are willing to coordinate with any investigation for the purpose of determining the real cause of this bombing," Kabalu said over DZBB radio. "We want this investigated. If they need our participation, we are willing to find out who is behind this attack."
Observers said there was a possibility the airport attack was carried out by Islamist guerrillas of Abu Sayyaf, the al Qaida-linked group that held two American missionaries and a Filipino nurse hostage for over a year. Missionary Martin Burnham and nurse Ediborah Yap were both shot and killed last June during a government rescue attempt.
The United States has roughly 400 U.S. service members based on Mindanao Island to train Filipino troops in counter-terrorism tactics. They are located at Zamboanga, about 300 kilometers (200 miles) east of Davao.
The Pentagon announced last week it had reached an agreement with the Filipino military that would be sending up to 2,000 more troops to the Philippines to help fight Abu Sayyaf guerillas on Jolo Island. The fighting force would include around 400 Special Forces soldiers and they would be allowed to engage in direct combat with the guerillas under command of the Philippines armed forces, according to the Pentagon.
The announcement sparked protests in the Philippines, an American colony from 1898 to 1946, and whose national constitution forbids foreign fighters on its soil. The arrangement has been suspended pending resolution of the constitutional issue.
It is not yet clear whether Tuesday's attacks may alter the prospects of the joint operations, but observers noted that terrorist acts may increase pressure on Filipino legislators to reconcile the constitution's wording with anti-terrorist efforts.