A 79-year-old Harlem man was killed last night when he was struck by a police car speeding to assist an officer, witnesses said.

Javier Jackson was crossing Broadway near West 136th when the marked cruiser hit him, witnesses said.

Jackson stepped into the busy thoroughfare from the median at midblock and against the light, and was sent flying, they said.

“The police were coming real fast with the siren on,” said witness Anselmo Sanchez, 42.

Police said the 30th Precinct officer behind the wheel had the lights on, as well. But witnesses said the car’s lights were off, and some who knew Jackson said he was hard of hearing.