Willie Davis Hines, Jr., 23, of Adelanto, was seen fleeing from his girlfriend's home late Wednesday afternoon. A neighbor made a domestic disturbance call after hearing the two argue.
The woman was en route to the hospital by the time police arrived at the 14500 block of Blue Sage Road.
After arriving at the hospital, her unborn fetus was determined to be dead, possibly as a result of the assault.
The woman remains in critical condition with major head and upper-body injuries.
Police have not located Hines, who is facing an attempted murder charge in the alleged assault on his girlfriend and a possible murder charge in the death of the fetus.
Investigators don't believe that he is armed, however, he would be considered dangerous.
Anyone with information regarding his whereabouts or the incident is asked to call the San Bernardino County Sheriff's Department at (800) 783-7463.
KABC-TV LOS ANGELES, CA contributed to this report.