I killed everyone around the mission target, but it seems not not trigger the next phase.
One problem was the truck-driver, he seemed to be inactive. I went into his truck and, trying to overwhelm him, but I couldn't. Instead V went to the driver seat and I could drive the truck away, with the driver still levitating in his former position. I shot him, but it did not help...

Edit: Killing everyone in the whole garage and quicksave+quickload didn't help. Loading a former Mission-Save (before passing the last gate) and killing everyone again helped. But I don't think, thats the way to go.