americans to leave the country after a deadly military crackdown against anti-government protesters. nbc's chief foreign correspondent richard engel is in benghazi, libya. richard? >> reporter: martin, the united states and the uk are examining worst case possibles now in syria. the u.s. state department said americans shouldn't travel to sear why, that americans in syria should leave while commercial transportation is still available. the uk saying that it is examining the possibility of evacuating all of its citizens from syria. these aren't steps taken lightly. the situation continues to deteriorate. human rights groups said today that 400 people have been killed in syria in the past five weeks. in the past five weeks of uprisings that now the syrian government is determined to use its military to stop. yesterday the syrian army went into the city of dura, several thousand troops backed up with tanks. today horrific scenes from inside dura.