A massive fire swept through the headquarters of Telecom Egypt in downtown Cairo on Monday, leaving four people dead and at least 27 injured, according to Egyptian authorities on Tuesday.

The blaze broke out in one of the rooms housing telecommunications systems and quickly spread through other floors of the iconic ten-story building due to its intensity. The structure was severely damaged, and as of Tuesday morning, firefighters were still working to extinguish remaining hotspots while smoke continued to rise from the upper levels, according to an AP photographer at the scene.

The four fatalities were employees of Telecom Egypt who were inside the building when the fire erupted, the company’s labor union confirmed. The Ministry of Health reported that 27 people had been hospitalized, with several already discharged. Others were treated on-site for smoke inhalation and did not require emergency transport.

Beyond the human toll, the fire also caused disruptions to essential services. Internet connectivity dropped to 62% of normal levels, according to NetBlocks, a global internet monitoring group. Mobile phone service and air traffic were also affected, though the Civil Aviation Ministry stated that suspended flights later managed to depart.

The Egyptian Stock Exchange was forced to halt trading on Tuesday due to widespread technical issues impacting its trading systems.

Minister of Communications Amr Talaat announced that all services will be fully restored within 24 hours, as operations have been temporarily rerouted to backup centers functioning as an alternative network.