A 64-year-old woman was raped by a man as she walked to work in what police believe was a racist attack.
The grandmother was in Langhedge Lane, in Edmonton, north London, at about 0500 BST on Sunday, when a man pushed her to the ground.
The suspect, thought to be Asian or Eastern European, seriously sexually assaulted the white woman.
The woman escaped for a short while but he gave chase and then raped her. She got away finally and raised the alarm.
Police said the woman's ordeal lasted for more than an hour.
The attacker spoke broken English and police said the language he used suggested the attack was racially motivated.
Detective Chief Inspector Richard Player said: "This was a brutal attack on a grandmother as she walked to work in the morning.
"Her ordeal lasted for over an hour and left her in considerable shock.
"It is vital that we apprehend this man before any other woman is put through such an ordeal."
The attacker is in his early 20s with dark hair and some growth on his chin. He is slim and about six feet tall.
The victim said the man wore long johns under his trousers.