MANILA, Philippines (AP) _ Philippine authorities combed wreckage, questioned a detainee and manned a tip hotline Sunday as they searched for suspects in five explosions that killed at least 14 people and left the nation on edge.

Jittery Manila residents awoke to a heavy police presence, grim media images of mangled bodies and the fear of more attacks. Embattled President Joseph Estrada faced growing anger from opposition groups.

Police said they took one person into custody after the blasts Saturday in the capital. They did not name the detainee, who they said was seen ``acting suspiciously'' and carrying wires near one of the explosion sites.

No one has claimed responsibility for the explosions, which hit a train, a bus, a gas station, a park and Manila's international airport.

Estrada made a brief televised address, saying, ``I assure you we will use all the forces of our law enforcers to halt this violence.''

Estrada's impeachment trial on corruption charges was in recess for the holidays. He denied opposition claims that he would use the bombings as an excuse to declare martial law.

The lack of known leads in the attacks fueled a crossfire of accusations, blame and suspicion.

Police hinted that Muslim rebels could be involved, while a presidential spokesman implicated communist rebels. The powerful political opposition said the attacks were aimed to distract the population from Estrada's trial.

Opposition leaders were planning a rally in Manila on Sunday to accuse Estrada's allies of staging the bombings and call for his resignation.

Graphic media images heightened a sense of insecurity in Manila.

Television showed an unconscious boy in the hospital after his leg was amputated, and one newspaper carried a front-page photo of a rescue worker carrying a little girl's mangled body.

The first four explosions Saturday came almost simultaneously around midday, sending thousands of panicked residents rushing from buildings.

One blast blew the front car of a train apart as it pulled into Manila's Blumentritt Station, killing 11 and injuring more than 60.

Later, police found a fifth bomb at a downtown gas station. Two members of a bomb squad were killed when it went off while they tried to defuse it.

Manila was on edge Sunday. Police were swamped with reports of suspicious packages, and several buildings were evacuated in false alarms. One package left on a counter in a shopping mall sparked a stampede from the building, but a bomb squad found it contained mangoes.

The attacks also increased political tension, already high with Estrada's fate hanging in the balance. His Senate trial is to resume Tuesday.

Accused of taking millions of dollars in illegal gambling receipts and tax money intended for tobacco farmers, the president is charged with bribery, graft, betrayal of public trust and violating the constitution.

A conviction would force Estrada from office and replace him with Vice President Gloria Macapagal-Arroyo, an opposition leader. The president and vice president are elected separately.

Police said the bombings had no apparent link to the trial and suggested the Abu Sayyaf, the smaller of two Muslim separatist groups in the southern Philippines, were to blame.

The government has been fighting the Abu Sayyaf rebels for 10 years, but the conflict intensified this summer. The blasts came a day after Manila-area police were put on alert for holiday bombing attacks by the rebel group.

On Thursday, police arrested Abu Sayyaf spokesman Hector Janjalani in Manila. They said he had several grenades and sketches of potential targets in the city.

But presidential spokesman Ernesto Maceda pointed to the New People's Army, a communist rebel group that has been fighting the government for more than 30 years.