The suspects shot their victim in the head with a single bullet at her home.
Police said the men fled on a motorbike following the attack.
The young lady was rushed to hospital but died in the ambulance before she got there.
“We are following several leads including a man who had a romantic relationship with the victim,” said Police Superintendent.
“We found an empty shell from a.45 calibre pistol at the scene and believe that two men had fled on a motorcycle.
“Witnesses said that two men had been seen in the neighbourhood before the shooting.”
Mary Christine Balagtas was killed at her home in Bulacan, the Philippines, on Wednesday morning.