According to the Upland Police Department, the two children - ages 4 and 6 - were taken by their uncle Wednesday, who does not have legal custody.
Police said the mother of the children told deputies that her brother, who was not immediately identified, was "unstable" and feared he would harm the kids.
Officers tried pulling the man over near Dewey Way and Foothill Boulevard but he failed to comply and took off, police said.
Police said the man led officers on a brief chase before he stopped and was taken into custody. That's when the man "spontaneously" said he "wanted to take the children to heaven," according to police.
Video of the encounter was posted on Upland PD's X account, which shows an officer with his gun drawn, telling the man to put his hands up.
The children were not harmed but were taken to a nearby hospital as a precaution.
The incident remains under investigation.