HILL AIR FORCE BASE — Whitney Snitchler was feeding her baby girl when a booming sound reverberated off the walls of her home in Riverdale.

The house shook for at least 10 seconds, and her first thought was that a bomb had gone off, and she wasn't too far from the truth.

An F-16 pilot taking off from nearby Hill Air Force Base had an "in-flight emergency" and flew back to land, jettisoning the plane's "external stores" — two 300-gallon fuel tanks and two unarmed 500-pound munitions, said HAFB Col. Scott J. Zobrist.

Military personnel say the resulting explosion, which was heard throughout parts of Davis and Weber counties about 4 p.m., was likely caused by one of the munitions hitting the ground in an "uncontrolled situation."

"We're used to having airplanes overhead that shake the windows a bit, but nothing like this," said Snitchler, 23. "I thought we were going down."

One of the unarmed ordnances is believed to have hit a "small, empty tin shack" in the northwest part of base, which likely resulted in the explosion, the colonel said. A nearby transformer and power lines also were damaged, causing a power outage throughout the military base.

"They landed on an uninhabited part of the base," he said. "The aircraft and pilot then landed safely at Hill Air Force Base."

Military officials cordoned off a 2,000-foot-radius area to search for remains of the munitions for a few hours, closing off the Roy entrance gate and evacuating countless military personnel and other staff. Within five hours, the two fuel tanks and munitions were accounted for in a remote, uninhabited area on the northwest side of the base.

Military explosive experts were still assessing how to best recover the munitions, officials said Thursday night in a press release.

Officials evacuated parts of the base out of concern that the then-missing ordnance could explode or "go off low order," Zobrist said.

Police officials shut down I-15 for a while near the base, but it was re-opened shortly afterward.

An eyewitness call to military officials about materials that may have landed near an irrigation canal just west of the Hill Aerospace Museum near the Roy entrance gate had hazardous materials crews and other officials searching around the canal, said Patrick Higby, commander of the 75th Air Base Wing.

Zobrist said environmental crews also were on site to begin cleanup efforts at the areas where the fuel tanks landed.

The colonel said the experienced pilot was following proper procedures. In emergency situations, pilots are trained to reduce their loads in order to land safely.