An air ambulance was forced to abort its landing when it was attacked by someone on the ground shining a laser into the cockpit.
The Wiltshire Air Ambulance was on a training flight over Chippenham on Thursday night when it was targeted.
The pilot said the aircraft filled with green light and he had to take evasive action.
As it flew away the person on the ground continued to shine their laser, he said. Police are investigating.
'Damage the pilots' eyes'
Wiltshire Air Ambulance helicopter HM22 was coming in to land at Hardenhuish School just after 19:30 GMT when the green laser was shone at it from a nearby residential area.
Chief pilot Matt Wilcox said: "We had to take evasive action and turn away because when a laser comes in it hits the Perspex on the aircraft and it reflects all around. It can actually damage the pilots' eyes.
"We had to overshoot but as we were departing this individual decided to keep shining the laser at us."
Using lasers to distract pilots can result in a prison sentence.
Mr Wilcox said had the helicopter been flying to a medical emergency there could have been more serious consequences.
"I'd like to say to the person involved to consider what might have happened if we had been coming in to land to offer their friend or family member life-saving help.
"We would not have been able to do that and the outcome might have been a lot worse," he said.
"Unfortunately people think it is acceptable to do this but it's exceptionally irresponsible and dangerous."
Wiltshire Police said anyone with information about the laser attack should contact the force on the 101 non-emergency number.