the gunman that police killed monday was a terrorist that americans had been warned about , the u.s. embassy said , adding u.s. citizens should stay vigilant because more terrorists remain at large .
Summarize the aforementioned text in a single phrase.

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
us embassy says suspect shot dead monday was terrorist it had warned about