Ramapo Mountain State Forest and Ramapo Valley County Reservation remained closed Thursday after hikers reported a series of encounters with aggressive black bears.

State officials closed nearly 1,500 square miles of park and set up traps to catch the bears.

"We had a couple of hikers that were chased and swiped at by the bear," says Dave Chandra, the director of New Jersey Fish and Wildlife, adding that the hikers had some scratches that could have been from a bear as well.

Four black bears had to be killed recently after they exhibited abnormal behavior and acted aggressively toward humans. One hiker told officials he had to throw his backpack at the bear to get away. Officials say killing the bears was the only option to keep the area safe.

Some people say humans are to blame for the bears' behavior. 

"You have to respect nature, and the only reason why [the bears] are acting up is because some irresponsible people are feeding them," says hiker Rich Cantisano.

Officials say the park will remain closed until biologists feel the threatening bears have either been put down or left the area.