Philippine National Police (PNP) chief Director General Arturo Lomibao said the suspects are believed to be members of the group Ley-Sam, which stands for Leyte and Samar, their home provinces.
From the provinces, the suspects later settled in different areas of Metro Manila and the nearby province of Rizal and Cavite, he said.
Arrested were Adrin Magat, 37, Jessie Fernandez, both from Caloocan City; Reynaldo Caldona, 38; Benjie Jacosalem, 25; both from Cainta, Rizal; Aurelio Isidro Jr., and Richard Seblante, both from Cavite.
"The neutralization of the syndicate was the result of well coordinated police operations with the cooperation of concerned citizens," Lomibao said.
The PNP chief said the six suspects were arrested in a series of police operations conducted by combined operatives of the Criminal Investigation and Detection Group (CIDG), Police Anti-Crime Emergency Response-National Anti-Kidnapping Task Force (PACER-NAKTAF) and the Quezon City Police District under Chief Superintendent Nicasio Radovan.
Police confiscated a 9mm Madzen machine pistol, a caliber .45 pistol, two .38 revolvers, two hand grenades and a motorcycle.
Lomibao said the group was behind the fatal shooting of businessman Shir Mon Choa and the wounding of his brother Shir Chuang Choa during a foiled abduction in Valenzuela City last July 12.
The brothers were on their way to work when the kidnappers blocked their vehicle on Mulawinan street in Cabral Industrial Park in Barangay Lawang Bato.
Records showed that the group was behind the kidnapping of a hardware owner in Angono, Rizal last April.
The Ley-Sam group robbed two Taiwanese traders in Meycauayan, Bulacan and pulled off a heist in Blumentritt last March .
The group was also tagged in the robbery of the a Metro Rail Transit station in 2003 and a junk shop in San Bartolome in Quezon City last month.