Rival gang members sparked a melee in a Manhattan courthouse Tuesday, leaving two people slashed and a hallway covered in blood.

Authorities took seven suspects in custody after the out-of-control fight broke out on the 13th floor of the criminal courthouse at 100 Centre St. around 12:15 p.m., law-enforcement sources said.

The two groups allegedly started jawing at each other outside the Part 93 courtroom, which escalated into a shoving match and eventually turned bloody, the sources said.

One person was brought to Bellevue Hospital, a 24-year-old man who was slashed in the hand.

A courthouse source said one of the two injured individuals was slashed by a scalpel likely made from fiberglass.

Photos showed blood splattered on a wall and floor of the hallway — with feathers from a torn puffer jacket scattered around bloodied napkins.

A spokesman for the state Office of Court Administration said the investigation was ongoing.

“At approximately 12:15 pm on Tuesday, Jan. 28, in a hallway of the Supreme Court Criminal Term at 100 Centre Street, two individuals sustained a slashing injury. New York State Court Officers immediately responded to the incident, facilitated transport to a local hospital, and initiated an investigation,” the spokesman said in a statement.

“The Court Officers took seven individuals into custody and recovered two sharp objects.”