Police say a melee between two gangs on the streets of Nyack Wednesday afternoon left two injured.

One teen was stabbed in the back and another was struck with a hammer during the fight that involved nearly 50 teenagers. An eyewitness, who wished to remain anonymous, says one teen was armed with a weapon that looked like a large club with a rock tied to it.

Det. Lt. Jim Brown of the Orangetown Police Department says the fight may have stemmed from an incident earlier in the day at Nyack High School.

?We believe it's a fight between a group of kids from the Nyack area and a group from the Spring Valley area,? Brown says.

After the brawl, the teens ran. Several law enforcement agencies are working on the case and trying to keep the area peaceful in the fight?s aftermath.

Five teens were arrested as a result of the melee. The two victims were treated and released from Nyack Hospital.