WASHINGTON — Four suspects, who were connected with a “criminal street gang,” face charges for a shooting in Silver Spring, Maryland, that took place 23 years ago, police said Wednesday.

All four were associated with the gang So Koh, which was active during the ’90s in Maryland, Montgomery County police said in a statement.

Police are charging Hiey Hien Vo, 42, and Kha Ngoc Do, 43, both of Silver Spring, and Phuoc V. Phan, 43, and Nhan V. Bui, 44, who have unconfirmed addresses. They have been charged with the attempted murder and conspiracy to commit murder of three victims during a June 21, 1994 shooting in the 8500 block of Piney Branch Road in Silver Spring.

Phan and Do are already incarcerated on unrelated charges; Bui is serving a sentence in a federal correctional institution, according to police. Police did not release further information about Vo.

Several members of So Koh are also persons of interest for the Jan. 12, 1997 killing of Hiek Chung and Chai Tan, which happened at the time in the King’s Kitchen Chinese Carryout at 9224 Warren St. in Silver Spring, police said.

Those with information about this homicide investigation or other unsolved homicides from the ’90s can call police at 240-773-5100.