Police in Grain Valley are warning residents to make sure their doors are locked at night after a recent rash of burglaries in the past few weeks. According to investigators the thieves get into the homes through unlocked back doors while homeowners are sleeping. Authorities say in some cases they are stealing from vehicles as well. Officers say the intruders are ready for a confrontation and are probably armed. If you know anything about these crimes you are being urged to contact the Grain Valley Police Department.