Detectives have been carrying out a forensic search at a house in Leeds after masked men used ammonium sulfate during a burglary.
West Yorkshire Police were called at around 6am after the burglary at the house on Strathmore Terrace, Harehills.
Three men had broken into the house and assaulted the people inside, throwing a white powder at a man and two women.
The white powder was later verified at ammonium sulfate, which is used in fertilisers and can cause irritation to the skin but does not leave long lasting damage.
Police said nobody was injured in the assault, but the male victim was taken to hospital to be checked.
The three suspects stole and drove off in a black BMW, which was parked outside.
A cordon was put up closing the entire street, although this was later scaled back to include just the house where forensics officers are examining the scene.
No arrests have been made in connection with the aggravated burglary, however one of the female victims was arrested for breach of bail and was in custody on Thursday morning.
One resident told the Yorkshire Evening Post: "There was so much noise. I looked outside and saw two men running down the street.
"There was a car following closely behind them. The emergency services arrived soon after, it must have been around 6am."
West Yorkshire Police said there was no wider risk to the area, and the incident was not connected to an earlier substance attack in Harehills this week in which a rough sleeper had a bleach-like liquid thrown at him.
Anyone who witnessed the incident or who has any information that could assist the investigation is asked to contact Leeds District Crime Team via 101 quoting crime reference 13190519760 or call the independent charity Crimestoppers anonymously on 0800 555 111.