Indonesian police on Saturday urged the public to remain calm a day after a suspected bomber killed himself and wounded 30 in a mosque at the police headquarters in the city of Cirebon, dpa reported.
The bomber set off the device as worshippers gathered for Friday prayers at the West Java city's police station. It was first suicide attack on a mosque in Indonesia.
The police chief was injured but in stable condition, police said.
"There's no need to panic," national police spokesman Anton Bachrul Alam said. "Leave it to police to deal with it."
Alam said 30 people were injured in the blast, including six seriously. Security had been tightened at police headquarters and stations across the country, he added.
He said the suicide bomber was a man believed to be between 25-35 years old but his identity had not been established. He declined to speculate on the motive for the attack.
The head of the national police medical division, Mossadeq Ishak, said investigators were determined to solve the case.
"The state must not defeated by terrorism," he said. "We are working hard to solve the case."
Friday's attack came almost two years after militants bombed the Marriott and Ritz-Carlton hotels in Jakarta, killing nine people and injuring more than 50.
Indonesian anti-terrorism police, trained and funded by the United States and Australia, have arrested or killed scores of militants suspected of involvement in past attacks.
Indonesia has been hit by a series of attacks blamed on al-Qaeda-inspired militants since 2000, including the 2002 Bali bombings in which 202 people were killed.
Terrorism analyst Noor Huda Ismail said Friday that militants linked to al-Qaeda could be behind the attack and the target was the police as a state institution.