The man,Â said to be 46-year-old, struck at Sheffield Council contractor Amey'sÂ depot on Olive Grove Road,Â Heeley, at around 6pm.
South Yorkshire Police said the man was known to those he targeted.
He is believed to have suffered '˜superficial injuries' in the incident and fled before policeÂ officers and firefightersÂ arrived.Â
Nobody else was harmed.
A police helicopter was deployed in the wake of the incident to try to locate the culprit but he has not yet been tracked down.
Detective Constable Newman HoltÂ said: 'Those involved in this incident are all thought to have known each other and we are actively looking to speak to the man involved.
'He is thought to have suffered injuries as a result of the incident and it's really important that we find him, to ensure his welfare, and speak to him about what happened.
'I'd urge anyone with information to please get in touch with us.'
Call South Yorkshire Police on 101 and quoteÂ incident number 646 ofÂ December 10.
Crimestoppers can also be contacted, anonymously on 0800 555111.