MANILA, Philippines - The bullets that killed 8 Hong Kong tourists in a Manila siege likely all came from the hijacker holding them captive and not from the police rescue team, a police spokesman said.

"We can say that with a certain degree of certainty," Senior Superintendent Agrimero Cruz, spokesman of the Philippine National Police, told reporters when asked if the bullets that killed the tourists came from the hijacker's weapons.

Cruz said the initial finding was based on witness accounts and testimony from the police involved in ending Monday's hostage crisis, as well as the number of bullets found on the bus.

However, in his briefing to the press on Thursday, he said the police investigation was still ongoing and that final conclusions had not yet been made.

Ex-policeman Rolando Mendoza held a busload of Hong Kong tourists hostage in a desperate bid to have himself cleared of extortion charges and get his job back.

After a standoff of about 10 hours, a police SWAT team assaulted the bus but its members were held at bay by Mendoza who police said used the hostages as human shields.

Cruz said the PNP leadership has ordered the relief of 4 SWAT team leaders involved in the Manila bus siege while an investigation is ongoing. Relieved were Chief Inspector Santiago Pascual, Senior Police Officer 4 Reynaldo Antonio, SPO3 Alfonso Gameng, and SPO2 Bernardo Espinosa.

Manila Police Chief District head Rodolfo Magtibay was also ordered relieved after the hostage incident.

"This was the decision of the PNP leadership. They were the team leaders. They were relieved so that they would not influence the records and the equipment; and the people deployed during the height of the crisis," he told radio dzMM.

He said the PNP has ordered all 10 SWAT members involved in the bus siege to make themselves available for forensic examination including paraffin test to determine who among them fired their weapons.

He said the PNP will also investigate why Superintendent Nelson Yabut, chief of the MPD’s Public Safety Battalion, was allowed to join the bus siege.

Footage of the bus siege showed Yabut carrying a .45 caliber pistol, and in general police uniform and a black police field cap. He was not wearing a bullet-proof vest and protective helmet, and was being covered by a policeman with a shield.  With Agence France-Presse