MANILA, Philippines——The National Bureau of Investigation is on the hunt for the killers of one of its operatives who was stabbed and shot him dead with his own gun during a robbery in Manila Monday night.

Two suspects in the killing of Special Investigator III Gil Yanesa, who was also a dentist, were reportedly in the custody of the bureau. However, no official would confirm it, saying that they were still conducting an investigation.

"We don't want to compromise our operations as this involved our comrade," said one official, who declined to be identified by name.

The remains of Yanesa, assigned to the NBI-Anti Kidnapping, Hijacking and Armed Robbery Division (NBI-AKHARD), 49, was brought to the chapel at NBI’s headquarters on Taft Avenue before noon Tuesday.

A Mass attended by his family, bureau officials and employees was held at the chapel in the afternoon.

An investigation being conducted by the Manila Police District showed that Yanesa was aboard a passenger jeepney on his way home on Gabriel Street in Tondo when the robbery happened.

The robbers, who were armed with knives, announced the heist while the vehicle was cruising along Road 10 near Lakandula Street, police said.

According to witness Medilo Marciano, 44, after the suspects announced the heist, the passengers immediately handed their valuables. However, Yanesa declined to give his wallet and mobile phone.

Marciano said Yanesa tried to reach for his gun, prompting one of the robbers to stab him. Another robber grabbed the victim's gun and shot him.

Police said the robbers took turns in stabbing the victim, who was left inside the jeepney as the other passengers scampered for safety.

The victim was pronounced dead on arrival at the Gat Andres Bonifacio Hospital in Tondo, Manila.

Chief Insp. Erwin Margarejo, head of the Manila Police District homicide section, said three suspects were nabbed during subsequent follow-up operations by operations of the PNP and NBI. The suspects' names were not released.

A young boy who witnessed the robbery and killing remains in NBI custody.