The police in the Northern Marianas believe money issues and emotional frustration sparked a shooting rampage that resulted in the deaths of five people, including the gunman.
They have named the gunman as Zhongren Li, a 42-year-old Chinese.
Li killed four local people at a closed shooting range where it is believed he was once the caretaker.
Two of the dead were toddlers, while a four year old girl remains in a critical condition.
Later, while driving past a tourist site he shot at a group of South Korean tourists - injuring eight of them, before killing himself.
One of the Koreans, a 39 year old man, is in a critical condition and has been airlifted to Korea for treatment.
A spokesperson for the police, Jason Tarkong, says Li had applied to take over the shooting range but the ATF, the law enforcement and tax collection agency, had turned him down.
"We believe the Chinese male was in the process of taking over the shooting range from the previous owner, who passed away. It's my understanding that the ATF had to shut him down because he didn't have the proper paperwork, his licencing and everything so, and it's my understanding also that the guns that were registered to that shooting range were also taken away and secured."
Spokesperson for CNMI Police, Jason Tarkong.