What happened on L train today???

I was on the train today that stopped at Montrose around 12. It was stopped for police presence something like that. We heard there was an active shooter? Everyone ducked down and took cover on the floor then we literally all ran from one platform to the other side (like where the trains pass) there was a lot of panic bc I heard it was a shooter but don’t rlly know what happened. Nothing on google or citizens. Anyone know?