Five units of Dublin Fire Brigade have been tackling a blaze at the Nirvana Head Shop on Capel Street in Dublin city centre.
Residents near the scene of the fire reported hearing an explosion at around 6.30am.
Gardaí say they are investigating the cause of the blaze, which spread to an adjoining shop.
Firemen had to break down walls to get to the source of the fire at the rear of the premises and a small number of nearby homes and businesses were subsequently evacuated.
AA Roadwatch says Capel Street will stay closed for most of the day.
There is no access from any of the approach streets and motorists are advised to take an alternative route.
Luas services are not affected.
Gardaí are advising caution as smoke is still hampering visibility on most of the adjoining streets to Capel Street and along the North Quays.
12/02/10 - 02/12/10