A 39-year-old man was jumped from behind in Central Park on Monday night, police said.

The man was walking inside the park, near West 86th Street, at about 8:30 p.m. when he was punched in the head from behind and knocked to the ground.

The suspect, in his mid-20s and about 5-feet-9-inches, then brandished a knife and beat him up, police said. The suspect grabbed the man's iPhone and BlackBerry before running further into the park, toward the reservoir.

The man was taken to Mount Sinai Hospital in stable condition.