Police are trying to track down a man who's been cutting open the pockets of L train riders and robbing them in Brooklyn.

Investigators say he has robbed at least seven people since February 18.

All of the incidents happened on Brooklyn-bound L trains in the early morning hours.

Police say the man has taken cell phones and wallets.

Some of the victims were asleep when they were robbed.

Anyone with information on the case should contact the Crime Stoppers hotline at 1-800-577-TIPS, or text CRIMES and then enter TIP577, or visit www.nypdcrimestoppers.com.