FLINT, Mich. (AP) - A Michigan school was briefly placed on lockdown following an emergency call about a person with a gun. Flint school district spokesman Bob Campbell says the lockdown order at Northern High School was lifted around 9:55 a.m. Thursday after police searched the building. No weapons were found. Campbell says some parents picked up their children once the lockdown was lifted, but school was continuing for the day. According to Campbell, a call made to 911 earlier Thursday morning claimed a person at Flint Northern was armed and making threats. The school was notified by police and initiated its safety plan. Campbell says police will continue to investigate, and there will be an increased security presence at the school about 55 miles northwest of Detroit throughout the day.