A car bomb exploded Monday near a military bus carrying troops on their way to work in northern Lebanon, killing at least five people and injuring 25, Lebanese security officials said.
A senior military official told The Associated Press that four soldiers were among the dead and the security officials said 22 of the injured in six area hospitals were soldiers.
It was the second deadly attack targeting troops in northern Lebanon in less than two months.
The security officials said the explosives-laden car was parked on the side of the road and was detonated by remote control as the bus drove in the Bahsas neighborhood on the southern entrance to the northern port city of Tripoli.
They said the explosives used were mixed with ball bearings to maximize casualties.
The blast, which tossed the car about a dozen meters (yards), occurred during the morning rush hour, according to the officials who spoke on condition of anonymity because they were not authorized to speak to the media.
Soldiers sealed off the area and prevented people from approaching the blast scene. The explosion shattered windows of cars parked in the area. Police forensic experts in plainclothes or in white uniforms and with several wearing masks searched for evidence in the bus wreckage.
An officer at the scene said the bus was carrying about 30 soldiers and was headed from the remote region of Akkar, from which many troops hail, through Tripoli and toward Beirut.
The bus, its windows shattered, sat motionless on the street, with its lights still flashing. A badly damaged civilian SUV that was behind the bus remained at the scene.
Khodr Kheireddine Hamad, 31, was sitting at a nearby gas station when the car exploded. He quickly ran for cover as the glass and other debris came falling down.
"The explosion was so big, it was deafening. Till now I can't hear properly."
Television footage showed pieces of flesh strewn on the road. The owner of the car later showed up at the site, according to several television stations, and was picked up by intelligence agents for questioning about the circumstances surrounding the explosion.
That suggested that the owner may have been unaware that his car was rigged.
The military reported the attack in a terse statement saying "once again the hand of treachery targets the military ... in a terrorist attack."
Tripoli has been rocked by sectarian fighting between pro-government Sunni fighters and pro-Syrian gunmen of the Alawite sect, an offshoot of Shiite Islam, that killed or wounded dozens in the summer before a truce was reached.
On Aug. 13, a total of 18 soldiers and civilians were killed by a roadside bomb packed with nuts and bolts near a bus carrying troops on a busy Tripoli street. It was Lebanon's deadliest bombing in more than three years.
Monday's explosion came two days after a massive bombing in the capital of neighboring Syria killed 17 people and wounded 14. Syria said on Monday the attack was carried out by a suicide bomber and that the vehicle came from a neighboring Arab country.
It did not identify the country. Arab nations Lebanon, Iraq and Jordan have borders with Syria.
Syrian President Bashar Assad has recently warned of extremists operating in northern Lebanon and beefed up his border troops along that frontier in recent days.
No group has claimed responsibility for Syria's explosion, the August bombing in Tripoli, or Monday's attack.
Tripoli, about 50 miles (90 kilometers) north of Beirut on the Mediterranean coast, is a majority Sunni city and is Lebanon's second-largest. The region there is known to be a strong base for Sunni militants.
In 2007, Lebanese troops fought Sunni militants of Fatah Islam group in a nearby Palestinian refugee camp. The three-month battle that left hundreds dead before the army crushed the militants.
Fatah Islam group claimed responsibility for a bomb blast that killed a soldier in Abdeh, near Tripoli, on May 31.
Sheik Daie al-Islam al-Shahal, founder of the fundamentalist Salafi Sunni movement in northern Lebanon, said Monday's attack was part of the conflict among "external forces" in Lebanon, rejecting suggestions that Sunni militants were behind it.
"The false allegations and haste do not help stability and cause tensions," said al-Shahal, Lebanon's most powerful Salafist leader.