Cairo , Egypt ( CNN ) -- A fire broke out in the Egyptian Interior Ministry on Tuesday in downtown Cairo following a protest earlier in the day . Flames could be seen on the roof of the multistory building , and a dark plume of smoke loomed over the city . People could be seen fleeing the building as it burned . The blaze was extinguished in under an hour . The ministry was the site of a peaceful protest Tuesday morning and afternoon , with thousands of ministry employees -- many of them police officers -- making demands , mainly for higher wages . Protesters at the building denied setting the fire , saying it originated inside . During the protest , some of them could be seen climbing on guard posts and the building 's roof . `` I suspect that an electrical circuit malfunction may have caused the fire because it started at the top floors of the police communication building inside the ministry , '' said Alla Mahmoud , Interior Ministry spokesman . `` The protesters did not enter . '' He said uniforms and old furniture are stored on the top floors , which would explain the thick smoke . The cause of the fire was under investigation , he said , and findings will be announced Wednesday morning . Several firefighters suffered problems due to smoke inhalation , a Ministry of Interior spokesman said . Another man was rushed away from the building in an ambulance , but the cause of his injuries was not clear . Before the fire broke out , a procession of thousands of demonstrators made its way from the Interior Ministry through Cairo 's Tahrir Square -- ground zero for protests that toppled longtime Egyptian President Hosni Mubarak last month -- and in the direction of the state television and radio offices . In a similar protest a few weeks ago , demonstrators set other buildings in the Interior Ministry complex ablaze , as well as cars . However , that fire did not grow to the size of Tuesday 's blaze . CNN 's Christine Theodorou and journalists Ian Lee and Mohamed Fahmy contributed to this report .
Ministry spokesman : Electrical circuit malfunction may be to blame . The fire has been set . Protesters denied setting the blaze . The mosque was the site of a protest earlier Tuesday .