Kym Lopez, a police spokeswoman for Negros Orienta province, said Mr. Degamo was shot while distributing aid to voters in front of his house.
Janice Degamo, wife of the governor and mayor of Pamplona, said the attack killed Mr. Degamo and five others. Four more people were shot, but their conditions were not immediately known.
The attackers fled the scene in three cars and later abandoned them in a nearby town. Police are hunting 10 suspects, including six gunmen.
"Governor Degamo did not deserve such a death. My husband was scheduled to meet voters on March 4," Ms. Degamo said in a video posted on Facebook. "Please give my husband justice."
Police cordon off the scene of the murder of the Governor of Negros Oriental, Central Philippines on March 4. Photo: PNP
President Ferdinand Marcos condemned the "assassination" of his political ally and warned the perpetrators that "surrendering now is your best option". "My government will not rest until the perpetrators of this cowardly and heinous crime are brought to justice," President Marcos said.
Mr Degamo, 56, is the latest target in a string of attacks on politicians in the Philippines. At least three politicians have been shot since last year's local elections.
After a recount, the Philippine Supreme Court last month declared Mr. Degamo the legitimate winner of the Negros Oriental governorship race. Initial results showed that Degamo's opponent won the election.
Governor Degamo also campaigned for Mr. Marcos during last year's presidential campaign.
In 2009, an attack on supporters of a politician running for governor of Maguindanao province left 58 people dead. The leaders of a powerful southern tribe and about 20 others were sentenced to life in prison.
According to VnExpress