The reported explosion on Tuesday evening that injured one man in a charity shop in Austin, Texas, was an incendiary device – not a package bomb, police say.
The authorities say it not is related to a series of recent parcel bombs in the area that have killed two people.
Instead an old military device donated to the store detonated.
The authorities have said the earlier blasts – involving package bombs and a tripwire – were all related.
President Donald Trump said “a very, very sick individual, or maybe individuals” carried out those blasts and pledged justice for the victims.
The city has been on edge after the attacks, and hundreds of police have been deployed to the area to investigate.
The Austin fire department said a man in his thirties received “potentially serious” injuries in the explosion at the Goodwill charity shop on Brodie Lane.
Local police later tweeted that “there was no package explosion” and that “items inside package was not a bomb, rather an incendiary device”.
At a special media briefing, police confirmed the incident happened at about 19:00 local time (00:00 GMT Wednesday).
They said one of the shop’s employees had found a box, which looked like a “military-type ordnance” or an “artillery simulator”.
The employee then asked another member of staff to get rid of the box. But the latter “initiated” it, causing the incident.
The unnamed member of staff was now “recovering well”, the police said.
Earlier in the day, a parcel bomb had exploded at a FedEx depot in Schertz, near Austin, slightly injuring one person.
FBI officials said another package at a separate FedEx facility in the area “was disrupted by law enforcement” on the same day. -BBC
