Indonesian police say a suicide bomber in Central Java province detonated explosives Sunday at a Protestant church packed with hundreds of worshippers, killing himself and wounding at least 20 others, some critically.

Authorities say the bombing in the city of Solo occurred just as people were exiting the church at the end of the service. Witnesses said the attacker was disguised as a church goer but was not thought to have been a member.

Indonesian President Susilo Bambang Yudhoyono condemned the attack, and said initial evidence shows it may be related to an attack on a mosque attached to a police station in West Java earlier this year.

Indonesia has been rocked by a series of attacks in recent years staged by the regional terror network Jemaah Islamiyah, including the 2002 Bali bombings that killed 202 people.