A New Mexico wildfire has breached the boundary of Los Alamos National Laboratory, one of the top nuclear weapons research facilities in the US.On Monday, officials said that they had detected "no off-site releases of contamination" and said the facilities face "no immediate threat".The lab was closed on Monday and was to remain so on Tuesday, while an evacuation order has been given to the surrounding town.Doug Tucker, Los Alamos fire chief said he could not guarantee the fire would not reach the lab.