A senior at Samuel Fels High School faces a list of charges after a gun he allegedly brought to school prompted a lockdown yesterday.

Juan Mejias, 18, has been charged with bringing a weapon to school, reckless endangerment and related offenses, Officer Tanya Little, a police spokeswoman, said.

Mejias was arrested at Fels, on Langdon Street near Sanger in Crescentville, yesterday by police, who locked the school down after another student spotted the gun about 10 a.m.

During their search, police found an unloaded revolver in a trash can inside the school's weight room, district spokesman Fernando Gallard told the Daily News.

Gallard said Mejias would be referred for expulsion.

Investigators are still trying to determine how Mejias obtained the gun and how he snuck it inside the school, Little said. Detectives have also indentified two other suspects in the incident. Their identities are being withheld by police because they are juveniles, Little said.

Mejias, of Chew Street near Front in Olney, remains in custody in lieu of 10 percent of $250,000 bail, court records show.