Students were taking classes in the school at the time of the accident but none suffered physical injuries.
The helicopter fell onto a small unoccupied apartment behind a home at 420 Casablanca St. five miles south of Calexico. People inside the house were frightened by the crash, but they were not injured.
Clementina Armenta de Pérez, the house's owner, said her two children were inside the house when the crash occurred.
"Thank God my family is OK," she said.
According to authorities, two of the soldiers were in critical but stable condition.
At least one was sent to 5 de Diciembre Hospital, owned by the federal government, according to a nurse at that hospital.
According to René Rosado, Mexicali fire chief, there was no fire after the crash of the Bell 212 Ranger helicopter due to the aircraft's low fuel.
The helicopter hit a light pole and some sparks could be seen, according to Enrique Sánchez Gastélum, a student at the nearby school. He said there was no explosion.
Ríos, one of the two women at the school who suffered from mental trauma, is Sanchez's teacher.
"She was looking at everybody, asking ‘What happened?' and we told her a helicopter crashed," he said.
Said Sergio Cruz Velázquez, who lives two blocks from the accident scene: "Me and my wife were inside our house and heard the helicopter's propeller, which sounded like what we see in movies when an accident is to occur."
Cruz said people are worried because helicopters fly over the neighborhood regularly at a low elevation. The Army base where the helicopter was heading is half a mile north of the accident site.
"On some occasions they fly very close to our homes," Cruz said.
Salvador Estrada, who lives in front of the Army base, said sometimes helicopters fly under the 90-foot high telephone antenna on the corner of his block.
Estrada said helicopters fly at least 10 times a day over his house.
Javier Gutiérrez-Vidal, Baja California's deputy government secretary, said the helicopters fly south into the Mexicali Valley to look for clandestine runways where smugglers can land their aircrafts loaded with drugs.
"It's obvious that always in a situation of public security, there are inconveniences for the citizenry," Gutiérrez said.
"They are doing their job. Unfortunately for the Villafontana residents, they are beside the military base, but this is an exceptional accident," he said.
The federal government is investigating the crash.