A heroic ROTC student fatally stabbed the crazed ISIS-linked gunman who opened fire inside an Old Dominion University classroom Thursday, preventing further carnage, law enforcement sources said.

Shooter Mohamed Bailor Jalloh, 36, gunned down an instructor before the unidentified cadet jumped into action to put an end to the suspected terror attack on the Virginia college campus, according to sources.

Jalloh, who was previously convicted of trying to support ISIS, walked into the classroom and asked if it was an ROTC class, sources told The Post.

Ex-National guardsman Mohamed Bailor Jalloh fatally shot a retired military officer at Old Dominion University on Thursday. AP

When someone told him it was, he began his trail of bloodshed, which the FBI is investigating as an act of terrorism.

Within an hour of the shooting, school officials said there was no longer a threat to staff or students.

“The shooter is now deceased thanks to a group of brave students who stepped in and subdued him – actions that undoubtedly saved lives along with the quick response of law enforcement,” FBI Director Kash Patel said in a statement.

The instructor, a retired military officer, was pronounced dead at the hospital.

Mohamed Bailor Jalloh, 36, was fatally stabbed by a heroic ROTC student at Old Dominion University.

Two other victims were also wounded in the hail of bullets, but appear to be in stable condition, authorities said.

Jalloh gunned down an instructor before the ROTC student successfully put an end to the suspected terror attack.

Bystanders getting evacuated from the Old Dominion campus after the shooting. AP

One of the victims brought themselves to the hospital, said Old Dominion University Police Chief Garrett Shelton at a press conference.

Both wounded victims are members of the Army Reserve Officers’ Training Corps at the university, said Lt. Col. Jimmy Delongchamp.

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“We will continue to coordinate with the university and law enforcement agencies as they investigate the incident,” Delongchamp told the Associated Press. “There’s still a lot more stuff we have to work out.”

The shooting is being investigated as an act of terrorism. AP

An ATF agent at the scene of the shooting in Norfolk. AP

Jalloh, a naturalized US citizen from Sierra Leone, was a member of the Virginia National Guard before he was sentenced to 11 years in prison for attempting to provide material support to ISIS, but was released from custody early in 2024, sources said.

“Old Dominion University faced a tragedy on our main campus,” Old Dominion University president Brian Hemphill said in a statement.

“I am grateful for the swift response of our police officers, emergency management personnel, and our partners at the City of Norfolk who promptly assisted the injured.”

With Post wires