Story highlights Report: More than 20 masked men broke into the hospital carrying assault rifles

Group was trying to free a drug kingpin who was in the hospital after a shootout with police

Rio de Janeiro (CNN) Rio de Janeiro's largest public hospital and one of the five designated to treat tourists during the upcoming Summer Olympic Games was attacked by armed gunmen during the weekend, leaving one person dead and two injured.

The attack deals another blow to a city struggling to show it's ready to host the games.

The raid took place early Sunday morning at the Souza Aguiar hospital. According to local authorities, the group was trying to free an alleged drug kingpin known as "Fat Family," who had been taken to the hospital a week ago following a shootout with police and was under police surveillance.

According to state news agency Agencia Brasil, more than 20 men broke into the hospital carrying assault rifles and hand grenades and wearing masks to cover their faces.

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Ana Paula dos Santos was in the hospital visiting her grandmother on the same floor when the raid took place.

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