Six people, including four children, have been shot dead at a house near the US city of Houston, police say.
One woman is in critical condition after being shot in the head, but she was able to identify the suspect and direct police to him.
After a chase, his car was surrounded and following a three-hour stand-off, he surrendered to police.
Police said the incident appeared to have started over a domestic dispute about a break-up.
However, the suspect's relationship with the deceased is not yet clear.
Police describe the suspect as a man in his 30s with a beard who was "cool as a cucumber".
When approached by officers he was "just sitting in his car looking out at us," said Sgt Thomas Gilliland.
Pictures from local broadcaster KTRK showed a small car in a cul-de-sac sandwiched between two lorries with a dozen police vehicles near it.
Police had been called to a house about 18:00 (23:00 GMT) and found three children and two adults dead, a Harris County Sheriff's Office statement said.
A fourth child died in hospital.