A man and a woman were fatally struck Thursday after he dragged her, screaming, in front of a Brooklyn subway train in what police believed was a murder-suicide, sources said.

Anthony Collins, 54, of Jamaica, Queens, grabbed his girlfriend, Cynthia Raiser, 42, of Brooklyn — who was struggling and shouting, “No, no, no” — at the Broadway Junction station at about 4:45 p.m. and pulled her along as he leaped in front of a Manhattan-bound C train, the sources said.

“They both jumped on the tracks together. He had a big gash on his head,” one witness, Kenneth Brown, 55, told The Post.

Sources said the couple appeared to be talking in a friendly manner when Collins’ demeanor changed just as the train entered the station. Collins — who, like Raiser, was married to another person — is said to have had a history of domestic violence.

Narda James was on her way to work when her train got stuck between stations after the incident.

“We walked from the next stop up on the C train,” she said. “They had us walk on the tracks.”