Patrols have been stepped up after a teenager was sexually assaulted in Tewkesbury, Gloucestershire.
The 19-year-old was pushed to the ground but kicked and bit her attacker, who ran off.
The incident happened at 0515 BST earlier, in an alleyway between Canterbury Leys and Northway Lane.
Police are appealing for witnesses. The offender is described as white, in his late 20s to early 30s, about 5ft 10in to 6ft tall, and medium build.
A force spokesman added the attacker was clean-shaven and had short brown hair and a "large pointed nose".
"Officers are increasing patrols in the area and will be speaking to any potential witnesses," he said.
"We would like to advise people not to be unduly concerned but to consider their personal safety.
"Try to avoid walking alone, if you are alone use well-lit routes."