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.
What happened on Tuesday?
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.
Skip Twitter post by @ATCEMS
FINAL Multiple assets #ATCEMS @AustinFireInfo @Austin_Police on scene Brodie Ln/W Slaughter Ln (1902) reported explosion: #ATCEMSMedics transported ~30s male with potentially serious, not expected to be life threatening, injuries to St Davids South Austin. No further info avail.
— ATCEMS (@ATCEMS) March 21, 2018
End of Twitter post by @ATCEMS
Local police later tweeted that "there was no package explosion" and that "items inside package was not a bomb, rather an incendiary device".
Skip Twitter post by @Austin_Police
#UPDATE: There was no package explosion in the 9800 block of Brodie Ln. Items inside package was not a bomb, rather an incendiary device. At this time, we have no reason to believe this incident is related to previous package bombs. #Breaking #packagebombmurders
— Austin Police Dept (@Austin_Police) March 21, 2018
End of Twitter post by @Austin_Police
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. It did not explode.
What about the previous bomb attacks?
They began in early March, with police confirming four attacks in Austin and one in Schertz, 65 miles (104km) south of the state capital.
Four of the five devices were hidden in parcels and one was probably activated by a tripwire:
- 2 March: A device explodes at Anthony Stephan House's home in Austin, killing the 29-year-old man
- 13 March: Draylen William Mason, 17, is killed and his mother is critically injured after he brings a package inside his home from the doorstep in Austin
- 13 March: Hours later, a 75-year-old Hispanic woman, who has not been named, is injured by another package in the state capital
- 18 March: A device injures two men who may have set off a tripwire while walking along a street in Austin
- 20 March: A parcel bomb explodes at a FedEx depot in Schertz, slightly injuring one person. Police said the parcel had been due to be shipped to Austin
What was President Trump's reaction?
"The bombings in Austin are terrible," he said on Tuesday.
"This is obviously a very, very sick individual, or maybe individuals.
"We will get to the bottom of it. We will be very strong."