Indonesian investigators said Friday that they believed Thursday morning's bombing of the Australian Embassy, which killed nine people, was carried out by three suicide attackers who had eluded a police manhunt after their fellow Muslim militants were captured during raids in July and August.

As police carried out interrogations in recent weeks, authorities grew increasingly worried that Jemaah Islamiah, an underground Muslim organization linked to al Qaeda, was planning a major terrorist bombing, investigators said.

Within the last week, Indonesian police circulated an internal memo warning of a possible attack, according to three officers involved in the investigation of the Thursday bombing. The memo focused on potential targets such as embassies, foreign-owned company offices and hotels, and the national police headquarters and counterterrorism training center, the investigators said.

Though the blast, which rocked the heart of Jakarta's modern financial district, killed nine Indonesians, it caused only minor injuries to staff members inside the well-fortified embassy. More than 150 people in the surrounding area along Rasuna Said Boulevard were wounded.

Indonesian and Australian investigators have determined that the attackers packed a Daihatsu minivan with explosives and then detonated them as the vehicle approached the mission's high metal gates, said Lt. Gen. Suyitno Landung, chief of detectives for the national police.

The Australian police commissioner, Mick Keelty, who arrived in Jakarta hours after the attack, told reporters that evidence indicated that the bombers used about 440 pounds of potassium chlorate, a common component of explosives.

Investigators now plan to determine whether body parts from three unidentified victims could be those of the suicide attackers. Indonesian police said they would compare the DNA of those victims with samples taken from family members of the three fugitives being sought by authorities.

"Militants who were arrested recently said there were three men who were ready to become suicide bombers," Landung said.

Police officials described the three as members of a group recently recruited in central and eastern Java to carry out attacks for Jemaah Islamiah. One of the three suspects had sent a letter to his family saying he was prepared to die, and he specifically mentioned two Malaysian leaders of Jemaah Islamiah, the chief bomb maker, Azahari Husin, and financier Noordin Mohammed Top, according to Inspector Gen. Paiman, a police spokesman who goes by one name.

The two men top Indonesia's list of most-wanted terrorist suspects. Immediately after the Thursday attack, Gen. Dai Bachtiar, the national police chief, blamed Azahari, who had previously been named a key suspect in the bombings of two Bali nightclubs in 2002 and the attack a year later on the JW Marriott Hotel in Jakarta, which together killed 214 people.

Speaking at a news conference here on Friday, Bachtiar said police may have come close to capturing Azahari and Noordin two months ago, when authorities raided a house in a Jakarta suburb near the international airport. "The men there were similar in appearance to Azahari and Noordin Mohammed, according to local residents," Bachtiar said. But the suspects fled, eluding capture as they had for nearly two years.

Australian Foreign Minister Alexander Downer told reporters after meeting with President Megawati Sukarnoputri that Indonesian police had received a cell phone text message warning of the bombing 45 minutes beforehand. Downer said the message threatened attacks on foreign embassies unless Indonesian authorities released Abubakar Baasyir, a radical Muslim cleric facing trial on charges of being the spiritual head of Jemaah Islamiah.

Indonesian police officials said they were unaware of such a warning.

In Canberra, Australian Prime Minister John Howard said intelligence agencies had warned of the possibility of another major attack in Jakarta. "The information they have available indicates that the number of operatives . . . is sufficiently large to support the fear that there could be another attack," he told reporters.

Special correspondent Noor Huda Ismail contributed to this report.

A security camera filmed this Daihatsu minivan believed to have carried explosives used in Thursday's suicide bomb attack at the Australian Embassy.Azahari Husin, left, and Noordin Mohammed Top, shown in undated police photos, were named as Jemaah Islamiah leaders in a suspect's letter home.