Snipers!

The girl and what seemed to be her 2 closest subordinates talked on and on for a while. Xavier learnt that the tranquilliser he had consumed wasn't lethal and would wear off within a day for average people. So even if he had consumed it, it would have likely worn off in half the time with his metabolism and physique that would be able to break it down twice as quickly.

Also, from what they said, Xavier also had a much better idea of what exactly their organisation actually was. It seemed as though it had once been part of something else that had split. And, although he wasn't sure of the details, Xavier had an idea of what they were previously a part of.

Meanwhile, whoever it was that was supposedly after her didn't seem to intend to destroy her organisation, which was quite an unusual aim. But it explained why there was such high security to get into and through the building, and also why she was so cautious.