A corporal in Republic of Korea's (ROK) marine corps went on shooting rampage on Monday, killing four fellow marines and wounding another on a Yellow Sea island base near the country's tense border with the Democratic People's Republic of Korea (DPRK), officials said.

The corporal was taken into custody on Ganghwa Island, about 70 kilometers west of Seoul, but his motive remained unknown, and the shooting was being investigated, Defense Ministry officials said.

The 19-year-old corporal, surnamed Kim, also was wounded, but it was unclear whether he tried to kill himself or was hurt when he was apprehended, the officials said. They declined to give their names because of office policy.

One of the slain marines was an officer, while the others were rank-and-file marines, the officials said. One died on the way to a nearby hospital, they said.

The weapon in the shooting could not be identified immediately, officials said. After earlier indicating no explosives were involved, they later said one grenade exploded during the rampage. They could not immediately verify a report by local broadcaster YTN that Kim detonated the grenade to kill himself.

The ROK stations hundreds of marines on front-line islands within easy striking distance of the DPRK. Last year, the DPRK shelled a ROK island, killing two civilians and two marines.

The waters are claimed by both countries. Boats routinely jostle for position during crab-catching season, and three deadly naval clashes since 1999 have taken a few dozen lives.

The tension has taken a toll on ROK's marines, who would take the brunt of any DPRK attack.

Questions:

1. How many marines were killed?

2. How many kilometers is Ganghwa Island from Seoul?

3. What local broadcaster said Kim detonated a grenade?

Answers:

1. Four

2. 70

3. YTN

（中國日報網英語點津 Julie 編輯）

About the broadcaster:

Lee Hannon is Chief Editor at China Daily with 15-years experience in print and broadcast journalism. Born in England, Lee has traveled extensively around the world as a journalist including four years as a senior editor in Los Angeles. He now lives in Beijing and is happy to move to China and join the China Daily team.