A suicide bomber blew himself up as police were praying Friday, wounding 28 people in the first attack on a mosque since extremists started targeting the predominantly Muslim country a decade ago. The victims -- including a local police chief -- were rushed to hospitals with nails, nuts and bolts embedded in their bodies, said Yeni Rahmawati, a hospital spokeswoman. The attack occurred in the West Java town of Cirebon. Though houses of worship are commonly targeted by militants in Afghanistan, Pakistan and Iraq, this was a first for Indonesia, and experts worry it could signal a "hardening" of local militants. Indonesia, a secular nation of 237 million people, was thrust into the front lines in the battle against terrorism in 2002, when the Al Qaeda-linked regional network Jemaah Islamiyah attacked two crowded nightclubs on Bali island, killing 202 people, most of them foreign tourists. Several, less deadly suicide bombings have targeted Westerners since then. The most recent was two years ago, which experts attribute in part to a successful police crackdown.