A couple and their 5-year-old son were tied up, locked in their car and burned to death during a robbery in southeastern Brazil, police said Tuesday.

Leandro Donizete de Oliveira, Eliane Faria da Silva and their son, Vinicius, were at home in Braganca Paulista, 60 miles north of Sao Paulo, when two armed men invaded their residence and took them hostage, police said.

The assailants ordered Silva, a store manager, to get the store keys from a colleague, who was also ordered into the car while they robbed the business of $9,368. Then they took the car to a deserted road, tied up the four, threw gasoline on the car and set it on fire.

The couple died in the car, and their son died later with burns over 90 percent of his body. The other victim was hospitalized in serious condition.

Police said a man with mild burns was arrested on suspicion of involvement in the crime.

"He hasn't cooperated with anything," Braganca Paulista Police Chief Paulo Tocci said. "This was a brutal crime — it shocked even veteran members of the force."