The National Weather Service says one of their instruments fell from the sky, prompting a Philadelphia bomb squad response. The device weighed about a pound and had been launched with a weather balloon about 165 miles away.

Mitchell Gaines, of the weather service in Mount Holly, New Jersey, says the instrument called a radiosonde took off Saturday from the agency’s office in Sterling, Virginia. High winds carried it to Philadelphia.

Radiosondes are sent up on high altitude balloons, taking and transmitting measurements to their home stations as they ascend. When the balloon reaches a certain altitude it pops, and the instrument floats to the ground on a built-in parachute. It has a postage-paid mailbag inside so finders can return it. reports the bomb squad responded when the radiosonde fell from the sky in northeast Philadelphia and struck a vehicle.