Junaid Mehmood was taken into custody late Thursday behind the Panera Bread restaurant on El Dorado at I-45 in Clear Lake, just hours after police made the gruesome discovery in Texas City.
Mehmood was audibly distraught in the back of a patrol car as he awaited transfer into Texas City police custody.
"I KILLED MY FAMILY," SUSPECT ALLEGEDLY CONFESSES
WATCH: Junaid Mehmood transferred into Texas City police custody
Investigators said he was "incoherent," emotional and yelling at times, and that he confessed to dispatchers, "I killed my family."
Officers said they were responding to a welfare check around 6:15 p.m. at the Pointe Ann Apartments. When they arrived on 10th Street North, they discovered the victims' bodies and found their mother with a gunshot wound to her head.
Kimaria Nelson, 24, underwent surgery and is currently listed as stable at University of Texas Medical Branch in Galveston.
Nelson's children were all found dead in the apartment she shared with Mehmood. Angela Pilot, 5; Prince Larry Brown, 2; and 2-month-old Ashanti Mehmood.
Junaid is the father of Ashanti.
Mehmood has been charged with aggravated assault with a deadly weapon and is being held without bond.
The children's cause of death has not been released. Texas City police say the investigation is continuing and more charges are expected to be filed.