( CNN ) -- At least 53 people were killed and eight others injured in a reported grenade attack Thursday at a casino in Monterrey , Mexico , the capital of Nuevo Leon , Red Cross officials said . The incident occurred around 4 p.m. local time ( 5 p.m . ET ) at the Casino Royale when two people aboard a vehicle arrived , and one threw three grenades into the building . There were conflicting unconfirmed reports from local media that the assailants poured gasoline on the building before setting it on fire . Between 20 and 30 people were trapped in the casino because of debris from the explosions , said Cmdr . Angel Flores with the Green Cross . Video from the scene showed a burned-out building as firefighters made rescue attempts to break the wall of the facade of the casino to release the smoke inside the building . Authorities had suspended rescue efforts Thursday night for fear that the building could collapse . Mexican President Felipe Calderon sent the following statement from his official Twitter account ( translated from Spanish ) : `` With deep consternation , I express my solidarity with Nuevo Leon and the victims of this abhorrent act of terror and barbarism . '' He added more : `` These reprehensible acts require us all to persevere in the fight against gangs of unscrupulous criminals . All the support to NL ( Nuevo Leon ) . '' About five families were outside the casino waiting for information from authorities , local journalist Javier Estrada reported . Gustavo Madrazo was one of those waiting outside the casino . He said his wife , Martha , and her sister , Miriam Gonzalez , were inside . Authorities have not identified any of the victims . So far , no representative for the company that manages the casino had arrived outside . The Mexican Army and state and municipal police forces were also on the scene . Alejandro Poire , Mexico 's top national security spokesman , said the federal government has made contact with local officials and that Calderon has spoken to the governor of Nuevo Leon to offer support . Poire said those who carried out the attacks will be held responsible . `` They will pay for their crimes . ... We will do absolutely everything ... to restore tranquility . '' The National Commission on Human Rights in Mexico sent a news release saying it has opened an investigation regarding the response to the events at the casino . `` The priority is to help safeguard the human rights enshrined in the Constitution of the United Mexican States and international treaties . The commission again makes clear that the insecurity in the country requires public officials responsible for implementing and enforcing the law , carry out preventive actions to protect society and away from any violence . '' `` The National Commission will monitor the actions taken by the competent authorities to respond adequately to the aggrieved persons . '' The NHRC says it has also sent personnel to the scene including physicians , psychologists and lawyers to work jointly with authorities . Nuevo Leon , in northeastern Mexico , has seen several grenade attacks so far this year . On August 13 , four civilians were wounded when an armed group fired two grenades at a jail in the municipality of Apodaca . In July , gunmen entered a downtown bar in Monterrey and shot 20 people dead . A public safety spokesman told CNN the attack was likely sparked by a dispute between organized crime groups for control of the El Sabino Gordo nightclub , where drugs were allegedly sold . Nuevo Leon and the neighboring states of Coahuila and Tamaulipas have been the scene of a series of clashes between organized crime groups . The Gulf Cartel and Los Zetas are vying for control of trafficking routes into the United States . In November 2010 , the federal government launched the Coordinated Operation Northeast , which involves sending more security forces to the area to tackle crime . CNN 's Nick Valencia contributed to this report .
NEW : Officials say the death toll in grenade attack is up to 30 . President Nuevo Leon responds to attack via his Twitter account . Grenade attack reported at a casino in Mexico , in northeastern Monterrey . Up to 53 people thought trapped in the casino because of debris .