Niniek Karmini, Jakarta, Indonesia – A popular singer. A former anti-terror chief. An outspoken critic of Islamic extremism. All have been targeted by parcel bombs sent by suspected Muslim extremists, leaving many in the Indonesian capital asking, "Who's next?"

Indonesia, a secular country of 237 million people, most of them Muslims, has a long history of religious tolerance. But a hard-line fringe has grown louder, and more violent, in recent years.

Critics say the government of President Susilo Bambang Yudhoyono – which relies on the support of Islamic parties in Parliament – is partly to blame. It has remained largely silent, even when mobs attacked Christians and members of Ahmadiyah, a minority Muslim sect, with knives, sticks and rocks, killing three people this year alone.

"Had the government pushed back from the beginning, it probably wouldn't have gotten to this stage," said Yenny Wahid, executive director of the Wahid Institute, which promotes a moderate and tolerant view of Islam.

As a result, she and others say, a small, intolerant group has seized the moral authority to decide who is a real Muslim and who isn't. "We, the nation, are paying a big price for that," Wahid said.

Four mail bombs have been sent this week, one exploding and injuring four as it was being detonated by police. All arrived in hollowed-out, thick books that said "Militant Jew" or "They should be killed for their sins against Islam and the Muslims."

The first packet was addressed to Ulil Abshar Abdalla, an outspoken critic of extremism and founder of the US-funded Islamic Liberal Network. Others were sent to Lt. Gen. Gories Mere, former chief of the police's anti-terror squad, and to Yapto Suryosumarno, a politician suspected of having ties to Jakarta's underworld.

The latest package was delivered Thursday to the home of Ahmad Dhani, a well-known singer who has butted heads with Islamic extremists, most recently over topless pictures of an actress.

With rumors swirling that many other parcels have been posted, talk about the bombings lit up social network sites like Facebook and Twitter on Thursday. "Celebrities. Politicians. Who's next?" some wrote.

For others, the biggest concern was that singer Justin Bieber and soccer sensation Giovanni van Bronckhorst might cancel planned trips to the capital.