Indonesia's president has ordered law enforcement authorities in the Islamic country to arrest the attackers who stabbed a Christian on his way to church and beat a female minister in the head with a wooden plank after she tried to help him.
Islamic hardliners are under suspicion because of previous attacks.
President Susilo Bambang Yudhoyono has been widely criticized for failing to crack down on extremists. He immediately called on police to investigate those responsible for Sunday's attacks.
We've questioned nine witnesses and have already identified the perpetrators," said local detective, Capt. Ade Arie. "But it's too early to comment or speculate on a motive."
The two Christians injuries were not life-threatening.
Local Police Chief Imam Sugianto said Asia Sihombing, a worshipper, was on his way to the field when assailants jumped off a motorcycle and stabbed him in the stomach.
The suspects also attacked Rev. Luspida Simanjuntak and hit her in the head as she tried to come to his aid.
"I was trying to help get him onto a motorcycle so we could get him to a hospital," she said.
Although the country has a long history of religious tolerance, one small extremist group has become more vocal and violent in recent years.
The Setara Institute for Peace and Democracy, a human rights group, said attacks on religious freedom by hard-liners were steadily increasing.
It said there have been 64 incidents - ranging from physical abuse to preventing groups from performing prayers and burning houses of worship - in 2010, up from 18 in 2009 and 17 in 2008.
"It's largely because Yudhoyono's administration is always so slow to step in," said Hendardi, a Setara activist, pointing to recent attacks on the Islamic minority sect, Ahmadiyah.