A botched stunt on a American TV show ended with an wayward cannonball smashing through a Californian family's bedroom.
Sheriff's deputies are still measuring how, exactly, the cannonball flew from a bomb range in the rolling hills flanking a San Francisco Bay area neighbourhood, rocketed into the front door of a home and through its master bedroom, before landing in a neighbour's parked minivan.
Hosts for the Discovery Channel show MythBusters fired the cannonball on Tuesday as they filmed an episode testing whether other types of projectiles shot from a cannon would pick up the same speed and have the same impact as the steel ball. Later, the production team plans to film flying stone cannonballs at a rock quarry in Northern California.
Instead of hitting a string of water-filled rubbish bins, however, the cannonball passed over the barrels, crashed straight through a protective cinderblock wall and careered off the hill behind it, said Alameda County Sheriff's Department spokesman JD Nelson.
"It missed the target and took kind of an oddball bounce," he said. "It was almost like skipping a rock on a lake. Instead of burying it into the hill it just went skyward."
No-one was injured, and the home's residents did not even wake up until the broken drywall settled on top of them, Mr Nelson said.
The show's co-hosts were due to go to the neighbourhood to speak with those affected and a meeting was called with production staff to understand what went wrong.
"We are really, really grateful and glad that no-one was hurt," co-host and executive producer Adam Savage said.
"Discovery is committed to making this right and making sure that everything that has been damaged is as good or better as before this started."
Producers have used the cannon they built at the county's bomb range, which is tucked in a valley in the suburb of Dublin, more than 50 times without incident, said Mr Nelson, the police department's liaison to the show.
Once it was launched, the cannonball travelled about 650 yards, bounced in front of the home, then tore through the front door and exited through a wall on the back of the house.
The projectile then bounced at least once more and crossed the road before smashing the window and dashboard of a gold minivan, where it came to rest.
Jasbir Gill, who owns the minivan, said he and his children had just come home.
"It's scary," he told the Contra Costa Times. "I was in the van five minutes before this happened."
Mythbusters, which is produced for Discovery Channel by the San Francisco-based Beyond Productions, issued a statement through publicist Katherine Nelson saying all proper safety protocol had been observed.
"Beyond Productions is currently assessing the situation and working with those whose property was affected," she said.
The show, according to its website, mixes "scientific method with gleeful curiosity and plain old-fashioned ingenuity to create (its) own signature style of explosive experimentation".
US president Barack Obama appeared on a segment last year aimed at testing whether the Greek mathematician Archimedes actually used only mirrors and the reflected rays of the sunset to set fire to an invading Roman fleet.