A British woman was murdered in Tenerife today, the Foreign Office said.
Spanish authorities said the woman was beheaded in a supermarket, according to the Associated Press.
Eyewitnesses reported seeing the killer run out of the store in Los Cristianos carrying the victim's head, before being tackled by security guards.
Sources said the woman, in her 60s, was "stabbed and decapitated".
The suspect is believed to be a homeless Bulgarian man with a police record.
A regional government spokeswoman said the killer is understood to have obtained a knife from inside the store to launch his attack.
Witness Colin Kirby, of Tenerifemagazine.com, said: "There were people shouting. There was a Hispanic-looking guy walking behind me, looking very scruffy, muttering to himself, carrying what I thought was a joke head by the hair. The blood - it just made me think 'Clash Of The Titans'.
"I thought 'The guy's a nutter, it's a joke'."
He added: "The security guards came out, they chased him across the road. By this time he's empty-handed. They got him on the other side of the road, just by the cultural centre. A couple of people tried to get him, they flattened him, got him on the ground."
Mr Kirby said he had spoken to an English couple who were in the shop at around 10.30am when the incident happened.
"They said this guy just walked in, pulled a big knife and started stabbing at her," he said.
Christina Perez, a legal representative at a nearby court, said a group of lawyers witnessed the man sprinting out of the Chinese store, carrying the head.
"They saw the man running out of the supermarket with the head in his hands.
"A security man from the complex ran after him and jumped on to him so he fell, and then he threw the head on to the road," she said.
Ms Perez, 38, added that her frightened colleagues darted indoors for safety.
"They were shocked. Some of them ran to the office and locked themselves in," she said.
"Everybody is shocked. It's a very safe area. You can usually go anywhere you want in the day or at night. This is really not normal."