Three students were stabbed outside a Brooklyn high school on Tuesday afternoon — less than an hour before a fourth teen was knifed in a separate attack in the same borough, police said.

The violence began outside Brownsville Academy on East York Avenue near East 98th Street just after dismissal at 2:50 p.m. when three male teens were stabbed during some sort of dispute, according to cops.

An 18-year-old was knifed in the chest and taken to Kings County Hospital in serious condition.

Another victim, 17, was stabbed in the ear and taken to Brookdale hospital in stable condition.

The third victim — also 17 years old — was cut in the chest and taken to Brookdale hospital in stable condition.

A suspect was taken into custody, sources said.

Four miles away in Red Hook, a 16-year-old was stabbed multiple times in the face near the intersection of Hicks and Mills streets around 3:30 p.m., police said.

The suspect, who was wearing a gray hoodie and black sneakers, ran off towards Columbia Street, police said. He remained on the loose Tuesday night.

The victim was taken to Maimonides and is expected to survive, police said.

It wasn’t immediately clear if the 16-year-old knew his attacker.