Authorities in Texas are baffled after being flooded with reports of burning debris falling from the sky.
Terrified onlookers were heard screaming when the mysterious "fireballs" were filmed mid-morning on Sunday.
They were captured by television cameras recording a marathon in the state capital Austin.
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No one has explained where the debris has come from, amid numerous reports of sightings to the Federal Aviation Administration.
The city's Sheriff's Office sent up a helicopter to investigate but it returned with no hard evidence.
There were initial concerns the fireballs originated from a collision of two space satellites last week. A US and a Russian communication satellite smashed together 500 miles above Earth.
