SAUGUS-Police responded to Walgreens on Walnut Street early Monday after a burglar broke into the store while an employee was still inside, police said.A 24-year-old Saugus woman was working at about 6:30 a.m. when she noticed someone break into the store, according to police. The employee locked herself in the break room where she called 911.She described the burglar was a male wearing a black hooded sweatshirt, a black mask while carrying a bag and some sort of tool, police said.The suspect was last seen leaving the store toward Route 1. Both Saugus and State Police searched the area and came up with nothing.Police continue to investigate the incident.