federal law enforcement source, here's what happened next. as the plane is boarding, agents are moving in. the decision is allow the plane to shut its doors. before the plane can push back, sources tell cnn, the door is reopened, fz is placed under arrest and removed from the flight before it ever leaves the gate. under intense questioning, another emergency, two more names on board the emirates flight appear suspicious, under abundance of caution, the plane is told to go back to the gate. >> i have a message for you to come back to the gate immediately. >> reporter: they were questioned and let go. the only arrest is faisal shahzad he is said to be cooperating with the investigation and detailing his travels and training. >> he's apparently talking about pakistan. do authorities believe him? >> cops don't believe anybody, anderson. they make you prove it, especially in these terrorists