Mexico's President Felipe Calderon walks after paying his respects to the relatives of the eight victims of a helicopter crash at the Campo de Marte military field in Mexico City, Thursday, Nov. 12, 2011. Mexico's Interior Minister Francisco Blake Mora and seven others died Friday in the accident in a mountainous area southeast of Mexico City. (AP Photo/Eduardo Verdugo)
In this video frame grab image taken from Televisa's Forotv via APTN, the wreckage of a helicopter carrying Mexico's Interior Minister Francisco Blake Mora is seen in a mountainous area of Mexico state southeast of Mexico City, Friday Nov. 11, 2011. The Mexican government said Friday, that Mora, Mexico's No. 2 government official next to the president, died in the helicopter crash with seven others, including the pilot. (AP Photo/Forotv-Televisa via APTN)
Gloria Cossio, widow of Mexico's Interior Minister Francisco Blake Mora, left, comforts her son Jose Francisco as her daughter Gloria looks on during her husband's funeral service at the Campo de Marte military field in Mexico City, Saturday, Nov. 12, 2011. Blake Mora died Friday in a helicopter crash with seven others at a mountainous area southeast of Mexico City. (AP Photo/Marco Ugarte)AP2011
Mexico's President Felipe Calderon, second left, and his wife Margarita Zavala, left, stand next to the coffin of Mexico's Interior Minister Francisco Blake Mora, during his funeral service at the Campo de Marte military field in Mexico City, Saturday, Nov. 12, 2011. Blake Mora died Friday in a helicopter crash with seven others, including the pilot. (AP Photo/Eduardo Verdugo)
The U.S. National Transportation Safety Board has sent a team of investigators to Mexico to probe the helicopter crash that killed the country's No. 2 official even though there are no indications that Friday's crash was anything other than an accident, according to the Mexican Communications and Transportation Secretary.
The board says it has also sent representatives of the Federal Aviation Administration to investigate Friday's crash in a rural area south of Mexico City. The crash killed Interior Minister Francisco Blake Mora and seven others.
The safety board said in a news release Sunday that Mexico requested help. The agents arrived Saturday.
The best way to honor the memory of such brave Mexicans as those we are bidding farewell to today is to continue working together, to continue fighting and with an even greater conviction for the things they fought for ... to transform Mexico into the country they wanted.
- President Felipe Calderón
President Felipe Calderón has asked Mexico's transportation secretary to carry out a thorough investigation into the causes of the helicopter crash.
Mexico's Transportation and Communications Department will remain the lead investigative agency.
Explosion and Fire Ruled Out
The helicopter crash that killed Government Secretary Jose Francisco Blake and seven other people earlier this weekend was not due to "some type of damage caused by an explosion or fire," Mexican Communications and Transportation Secretary Dionisio Perez Jacome said.
Experts drew this conclusion from "visual inspections" conducted at the accident scene, the secretary said.
The helicopter's wreckage was found scattered in a relatively small area in Chalco, a city in Mexico state, which surrounds the Federal District and forms part of the Mexico City metropolitan area, Perez Jacome said.
There are no indications that Friday's crash was anything other than an accident, the secretary said.
It is "very probable that the pilot (Lt. Col. Felipe Bacio Cortes, who died in the crash) penetrated" a fog bank and hit the ground for unknown reasons, Airport and Allied Services Administration director Gilberto Lopez Meyer said.
A state funeral was held in Mexico City on Saturday for Blake and the other seven victims of the chopper crash.
"The best way to honor the memory of such brave Mexicans as those we are bidding farewell to today is to continue working together, to continue fighting and with an even greater conviction for the things they fought for ... to transform Mexico into the country they wanted," Calderón said.
Blake was "a great human being" and an "honest, hard-working, loyal, patriotic and committed" public servant, Calderón said.
The president presented the families of each of the victims with the flags that had been draped over the caskets.
Three Cabinet secretaries have now died in aviation accidents in Mexico since 2005.
Many of those in attendance were reminded of the funeral of former Government Secretary Juan Camilo Mouriño, who died in an aviation accident three years ago.
The 37-year-old Mouriño died in the crash of a small plane in Mexico City on Nov. 4, 2008.
Security Secretary Ramon Martin Huerta died in a helicopter crash in Mexico state on Sept. 21, 2005.
The 48-year-old Martin Huerta had joined President Vicente Fox's Cabinet on Aug. 13, 2004.
Martin Huerta was in charge of implementing the government's strategy to combat drug cartels and other organized crime groups, a responsibility that later fell to Blake and Mouriño when they took office.
Based on reporting by the Associated Press and EFE.