PHILADELPHIA (CBS) -- Philadelphia police are investigating after a 30-year-old man found in the Schuylkill River died Tuesday evening.

According to police, the unidentified man was found just after 6:15 p.m. in the Schuylkill near the 2400 block of Walnut Street in Center City. 

Chopper 3 flew over the area earlier where they saw the water rescue taking place.

Emergency medical services responded to the area where they officially pronounced him dead at 6:50 p.m., police said.

It's unclear how long the man was in the water before authorities found him.

The Philadelphia Police Marine Unit is still in the area investigating.