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MANILA, May 31 (Reuters) - Police chased armed robbers through the streets of the Philippine capital during rush hour on Thursday after they held up a bus, and at least five people were killed in an exchange of gunfire.

Pedro Tango, police chief of Manila's northern district, said four people were arrested after the car chase and running gunbattle along Manila's major highway.

"One of the men in our custody was claiming he was a hostage," Tango told reporters, adding that investigators were still piecing together the evidence and witnesses' testimonies to get a clear picture of the incident.

Bella Mamaril, one of dozens of commuters on the bus, told a local radio station the drama began when five well-dressed men announced the robbery minutes after they had boarded the bus in Manila's financial district.

Armed with handguns and a grenade, the five collected the commuters' cash, jewellery and mobile phones, but some passengers managed to alert the police before they could get off.

Chasing police officers stopped the commuter bus by shooting out its four tyres, but the gunmen fought back and escaped holding three of the commuters as hostages, commandeering a van.

Two people, including the driver, were killed during the bus robbery and initial gunbattle, police said, adding the three hostages were rescued unharmed.

Magtanggol Gatdula, police chief of Quezon City, said the van driver was wounded but was rescued when the gunmen were cornered while trying to commandeer a dump truck.

Tango said another man was killed in the chase. Two more were killed and four captured during a gunbattle around the dump truck.

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