The US Embassy for Ukraine is Tweeting important updates and evacuation routes from Ukraine. Below is the link to follow these updates in real time on twitter.
https://twitter.com/USEmbassyKyiv?ref_src=twsrc%5Egoogle%7Ctwcamp%5Eserp%7Ctwgr%5Eauthor
Evacuation and Safety Updates from the US State Department:
https://travel.state.gov/content/travel/en/traveladvisories/ea/information-for-us-citizens-in-Ukraine.html