Church leaders in South Korea have asked for prayers after North Korea fired dozens of artillery shells on Tuesday, killing two South Korean marines and injuring more than a dozen people.

It was the first direct artillery attack on South Korean territory since the 1953 Korean War Armistice Agreement, according to South Korea's Yonhap News Agency.

The Christian Council of Korea's general secretary, the Rev. Kim Woon-Tae, said he couldn't help but feel shocked and worried after hearing the news.

He noted that it hasn't been long since a South Korean warship, the Cheonan, was sunk. It is suspected that North Korea torpedoed the warship that killed 46 sailors in March.

Some 100 artillery rounds were fired at Yeonpyeong Island Tuesday afternoon. The island is home to more than 1,600 residents, mostly fishermen and their families, and a marine corps base. South Korea's soldiers responded with more than 80 rounds of artillery. The exchange of fire lasted for about an hour.

South Korean President Lee Myung-bak said retaliation is needed, calling the provocation "an invasion of South Korean territory," as reported by Yonhap.

"I think enormous retaliation is going to be necessary to make North Korea incapable of provoking us again," he said, according to the South Korean news agency.

Stephen Bosworth, the U.S. special envoy on North Korean denuclearization, has urged restraint on both sides.

The United States condemned the attack and called on North Korea to halt "its belligerent action and to fully abide by the terms of the Armistice Agreement."

The 1953 agreement was intended to be a temporary measure of truce but has remained in place today with no peace treaty ever signed.

Pastor Rick Warren of Saddleback Church in Southern California has urged prayers.

In an early tweet, he stated, "Our South Korean churches ask for prayer as North Korea fired artillery shells across the border injuring 4 soldiers."

Meanwhile, CCK's Kim said he's praying for stability, peace and cooperation on the Korean peninsula as tensions remain high.

CCK has a membership of 63 denominations representing 10 million Christians in South Korea.