A 40-year-old Brisbane man has blown off his hand while mixing chemicals to make homemade rockets.
Queensland Police said the man's four-year-old son and a 74-year-old man were also in the house when the explosion blew out windows and sent a shock wave through the home.
They said all three people were lucky to be alive as the force of the explosion could have been deadly.
The man was taken to hospital with a broken leg, a missing hand and other injuries.
The toddler's mother was at work when the chemicals blew up about 8:00am.
Police say the man had been making rockets for a while, possibly to entertain his son.
"He's had a few successful launches in the past," Inspector Geoff Acreman said.
"We are very lucky we are not talking about three fatalities."
It is understood the 74-year-old and the toddler had been watching the man make the rockets but went upstairs before the explosion.
Police and paramedics have urged people not to mix or play with chemicals, even those commonly found around the house.