A girl of 13 was taken to hospital after being headbutted outside Sainsbury’s in Calne.
She was standing in front of the store, in The Pippin, with friends when she was attacked by a 16-year-old girl at about 7.50pm on June 29.
She was able to give a good description of the girl to Calne PCSO Mark Cook, who told her to stay there while he searched the area.
He found the 16-year-old walking past the library on The Strand and she admitted the headbutting.
The injured girl was taken to hospital by her father after a paramedic suggested she might have broken her nose.
PCSO Cook, who was out dealing with another case, said the girl had not been arrested but the matter was still being investigated.
He said: “I did not want to leave the injured girl, but I knew that the offender would still be close by and I wanted to catch the person responsible for this attack.
“I ensured that the girl remained at the location in the care of her friends.
“This was an unprovoked attack on a young female and this sort of behaviour will not be tolerated in our town.
“I was in the right place at the right time to be able to respond and the offender was quickly located.”