militias took over government buildings there. nbc's ayman mohyeldin has the latest. >> reporter: pro-russian separatist militias have again taken over a police station, this time in a city in donetsk. it's seven days in a row where these pro-russian militias, well-armed with military precision in very crisp uniforms that many believe say are backed by russia, that they've been able to take over these buildings and that has pushed the country into a very difficult position. the ukrainian government has given an ultimatum for them to lay down their weapons and leave these buildings, or risk having the armed forces come in and use force to clear them out. the problem in doing so, it could possibly provoke russia, which has 40,000 soldiers on the border. natalie? >> thank you, ayman mohyeldin. >>> firefighters in chile are struggling to contain a massive