Thieves who stole canisters from a yard at Shoreham Harbour ran over a man in his seventies as he tried to stop them.
Sussex Police said: “A man was seriously injured when he was run down by people he was trying to stop stealing gas canisters from a yard in Southwick.
“Emergency services were called to the Lady B Marina industrial estate in Albion Street at 11.56am on Monday (27 July).
“A man in his seventies was found with a suspected broken pelvis after a white flatbed vehicle made off from the scene colliding with him as it did so.
“A National Police Air Service helicopter was deployed to assist ground units in the search for the vehicle, which had orange red canisters in the back, along with scrap metal.
“It is believed that the flatbed may have been the same one seen in suspicious circumstances around the harbour about an hour earlier.
“However, despite extensive searches, it was not located.
“Anyone with information about the incident or the vehicle is asked to report online or call 101 quoting Operation Sandway.”
