Police said an undercover officer made a drug buy about 12:50 a.m. on Kuhio Avenue near Walina Street from a man and a woman standing next to a pickup truck.

When the officer's backup arrived he noticed another packet of methamphetamine in the lap of one of the other two men seated in the truck. When that man was removed from the truck, several more packets of drugs were visible as well as the hand grenade, police said.

Officers from the Police Department's specialized services division were called in to remove the grenade, which police said appeared to be authentic.

Three men — ages 37, 38, and 39 — and a 23-year-old woman were arrested for suspicion of a variety of felony offenses, including third-degree promotion of a dangerous drug, possession of drug paraphernalia, methamphetamine trafficking and possession of a prohibited explosive device.

The hand grenade was later turned over to agents from the federal Bureau of Alcohol, Tobacco and Firearms.

Man allegedly threatens to kill wife

A 41-year-old man was arrested yesterday after he allegedly terrorized his wife and threatened to kill her.

The woman, 38, said her estranged husband came to her home in Hawai'i Kai about 9:10 a.m. and began to argue with her.

Police said the wife went inside and locked the door, but the husband broke through the front door, grabbed a knife and pressed it against the woman's stomach.

The wife was able to break free, run out the back door and call police, who went to the home and arrested the man for suspicion of first-degree terroristic threatening.

Suspect arrested for alleged sexual assault

A 21-year-old Pawa'a man was arrested in Waipahu yesterday as a suspect in the sexual assault of an 18-year-old woman.

The woman told police she was held against her will and assaulted by a male acquaintance between 11 p.m. Saturday and 8 a.m. Sunday.

Police arrested the man for suspicion of two counts of first-degree sexual assault, kidnapping and abuse of a family or household member.

Brothers' fight ends with broken wrist

A Wai'anae man was arrested yesterday after he allegedly attacked his juvenile brother Sunday, breaking his wrist.

Police said the older brother became angered by his younger brother who was arguing with their mother, making her upset.

The younger brother was treated for a broken wrist and was later taken into custody by state child welfare workers. The older brother was subsequently arrested for suspicion of second-degree assault.