The one reward was for information that could lead to the arrest of the suspects who dragged a four-year-old boy outside a hijacked car in Reiger Park on the East Rand on Saturday, said Colonel Noxolo Kweza.
The boy died.
The other incident involved a five-year-old boy who was still missing after the car he was travelling in with his father was hijacked in Bronkhorspruit on Tuesday.
The hijackers fled with the car and the boy inside.
In Reiger Park, police said the boy was travelling in a City Golf with his mother, father and sister on Saturday night when the family was approached by three men.
They ordered the family to get out of the vehicle and the four-year-old was left in his safety belt.
"The four-year-old was left in his safety belt. They [the hijackers] got in the car and drove away," Lt-Col Khensane Magoai said.
Magoai said it was unclear how it happened but the boy was then dragged along; hanging outside the car door by his safety belt.
"He was dragged along until Boksburg. The hijackers then abandoned the vehicle and the boy was dead."
Reiger Park is about 8,5km from Boksburg.
Magoai said that no arrests had been made yet.
"We are still searching for the suspects."
"Gauteng provincial commissioner Lt-Gen Lesetja Mothiba said a task team consisting of members from the provincial office and the station under the leadership of Maj-Gen Tebello Mosikili has been established to investigate both incidents," said Kweza.
President Jacob Zuma is calling on the public to help police find a child who went missing when his father's car was hijacked, the presidency said on Sunday.
Five-year old Mongezi Phike was with his father in Bronkhorstspruit when their car was hijacked by four men.
"We also call on law enforcement authorities to spare no effort in seeking these criminals and bring them to justice...," Zuma said in a statement.
"We urge members of the community to help the police in their work so that Mongezi can be brought home safely."
Beeld Newspaper on Saturday reported that the incident happened on Tuesday night and the boy was still missing.
Mongezi and his father were in a car at an intersection in Masada, Bronkhorstspruit, when four men approached.
Two of them were armed.
A family friend said the gang allegedly tied the father's hands and feet with wire, covered his head with a plastic bag and wrapped tape around his neck.
His identity document, wallet, credit cards and phone were taken.
The friend said the father was hit on the head and left for dead at a construction site, while the hijackers fled with Mongezi.
The father was later found and taken to a hospital in Delmas.
"We cannot imagine the pain and sorrow that [the child's] family is going through," said Zuma.