A man has been arrested by detectives investigating three shop fires - one of them fatal - which are thought to have been racially motivated.
One man died and three were hurt in the Pricecutter fire
The 33-year-old, from Stockwell, south London, is being questioned by police about the murder of Khizar Hayat and the other fires - all in the capital.
Mr Hayat died on 27 April in a Pricecutter shop near the Oval, after a man threw a firebomb into the store.
Two of his colleagues escaped with minor burns, a third is critically ill.
Police had warned Asian-owned businesses in the area to ensure they had an escape route planned following speculation the attacks could be racially-motivated.
A bottle filled with accelerant was thrown into a newsagent's in Tulse Hill, south London, at lunchtime on 14 April and hit a customer's legs causing burns, but no-one else was injured.
Six days later another bottle, filled with petrol and set alight, was thrown into an off-licence in South Norwood.
Last Thursday's attack took place in the middle of the afternoon, on a busy street within sight of Lambeth Police headquarters.
A man was seen throwing a lighted object into the Pricecutter shop before running off.
He was chased by police who lost him in nearby Handforth Road.
Four members of staff at the Pricecutter store were trapped inside as the building was engulfed in flames.
Two decided to run through the fire into the street and escaped with minor burns.
Mr Hayat, 40, and a colleague headed to the back of the shop. He was later found dead and his co-worker is critically ill in hospital.