He probably held the knife to the throat of one, and the others didn't want to be the cause of her death.

But the guy who made the phone call didn't exactly use the time he had very well. "You need to help me" doesn't give a dispatcher or the police much information. "Man with a knife" or "He's going to kill us" would have been more appropriate. People need to learn to get the important information out first, elaborate later, if there's time.

But the perp had to have a lot of nerve to jump the four of them, not really knowing how they would react. Or he's crazy.

But "divide and conquer" can have another meaning, also.

Sue