"As of now, ten people have been killed in this incident," Mehdi Rezai, the deputy head of the Mashhad fire department, told the ISNA news agency, adding that five wounded people had been hospitalized.
Rezai also noted that 15 neighboring buildings had been damaged by an alleged boiler blast that had caused the collapse. The official added that the authorities were working to determine the exact reason behind the incident.
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The city of Mashhad is located in the northeastern part of the country, some 900 kilometers (550 miles), northeast of the capital Tehran.