Jose Pedro Rojas-Martinez, 23, is charged with capital murder after allegedly stabbing his children and their mother.
It happened around 1:30am in the King's Row mobile home park, which is off Telephone Road near Fuqua just north of Beltway 8.
Neighbors told us they heard screams and broke windows in an effort to rescue the victims.
"As [officers] approached, there was a male Hispanic suspect holding a female at knifepoint. The female was bleeding," Houston Police Department Homicide Division Sgt. Eli Tisneros said.
HPD said the two young children were lying on the floor -- an eight-month-old girl and a two-year-old boy. Both had been stabbed.
"When the officers arrived, [Rojas-Martinez] was making attempts to slash his own throat," Tisneros said.
One neighbor caught the confrontation with police on video. You can hear police shoot the suspect with a Taser gun and then wrestle him to the ground.
Police said the entire family was taken to the hospital. The eight-month-old girl died there. Her mother and brother underwent surgery. At last check, their conditions were unknown.
Police continue to search for clues to what led to this tragedy, which left neighbors in shock.
"It's terrible," neighbor Hortenza Hernandez said. "I got the chills when I heard."
Police say Rojas-Martinez only suffered minor injuries. He was checked out at the hospital and released into police custody.