MANILA, Philippines -- A bomb explosion that killed two people in a Muslim community in Manila was sparked by a personal feud, Philippine police officials said Sunday, but the Islamic State group claimed its fighters were responsible.

Police said a package being delivered by a man exploded late Saturday in downtown Manila's Quiapo district, killing him and another man receiving it at a Shiite centre. Police said four others were wounded.

Another explosive, either a homemade bomb or a grenade, went off more than two hours later near the scene of the first blast and wounded two policemen deployed to help secure the area and investigate the bombing, according to authorities.

Metropolitan Manila police chief Oscar Albayalde said the bombing apparently was set off by a personal feud, adding the package that contained the explosive was intended for a specific person who may have been the target of the attack.

Albayalde called for public vigilance following the bombing, the second in more than a week in Quiapo, a popular transportation, shopping and religious hub mostly for the working class in the capital. The Manila police went on alert following the explosions.

The Islamic State group, through its Aamaq media arm, claimed responsibility for the Quiapo explosion, saying in a brief statement that "five Shiites have been killed and six others injured by detonating an explosive device by the Islamic State fighters in central Manila."

The death toll differed from details released by the police and other officials in Manila.

There have been fears of the Sunni-Shiite violence spreading to the largely Roman Catholic Philippines, home to minority Muslims who are mostly Sunnis in the country's south. A Shiite centre was bombed in the south in 2015 and two local Shiites were killed in an attack near Manila that same year.

A pipe bomb also exploded in Quiapo on April 28 while President Rodrigo Duterte's administration was hosting an annual ministerial meeting of The Association of Southeast Asian Nations in a convention centre a few kilometres (miles) away.

Albayalde and other police officials said the April 28 blast was triggered by a gang feud and unrelated to Saturday night's bombing.

Police, backed by a SWAT contingent, early Friday raided the house of a suspect in that explosion and found materials to be used for two more pipe bombs, along with shotgun ammunition and electrical bomb parts.

The suspect, who was only identified as Saro, was not in the house in Manila, according to a police report.

The bombings came amid ongoing military offensives against the Abu Sayyaf and other groups, which have pledged allegiance to the ISIS group.

Associated Press writer Maamoun Youssef in Cairo contributed to this report.