Thieves stole catalytic converters from NHS staff's cars while they were parked outside a hospital.
Two cars belonging to hospital staff at Worcestershire Royal Hospital were targeted on Sunday.
It comes after parts were stolen from four nurses at Royal Stoke Hospital in Staffordshire last week.
West Mercia Police said it was "disappointing" to see healthcare workers targeted by thieves during the coronavirus crisis.
"I cannot emphasise enough how disappointing it is at a time when our health care professionals are risking their lives to look after us that they would be targeted in such a manner," Det Insp Jack Taylor said.
Police said two hospital workers noticed their cars making strange noises after they returned to their vehicles after finishing shifts on Sunday.
The force said there had been a recent increase in thefts of catalytic converters due to a rise in the value of metals they contain.
It has launched an appeal for witnesses and said there will be more officers patrolling "to deter potential offenders".
In a car's exhaust system, catalytic converters clean up harmful gases before they exit the exhaust pipe.
Police in London reported a huge rise in thefts in 2019 as the price of precious metals in catalytic converters skyrocketed.
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