A disabled Christian girl has been arrested accused of breaking Pakistan's strict blasphemy laws.
The teenager, who has not been named, and is reported to have Down's Syndrome, was taken into custody after hundreds of neighbours surrounded her house amid claims she had burned religious papers.
President Asif Ali Zardari has asked the Interior Ministry to look into the case.
The outrage among the local community demonstrates the deep emotion that suspected blasphemy cases can evoke in the conservative Muslim country, where rising extremism often means religious minorities live in fear of persecution.
In Pakistan anyone found guilty of insulting Islam's Prophet Muhammad, or holy book, the Koran, can be sentenced to death.
Pakistani police said that the girl was being held for 14 days while authorities investigate.
"About 500-600 people had gathered outside her house in Islamabad, and they were very emotional, angry and they might have harmed her if we had not quickly reacted," a spokesman said.
"Some Muslims from the area claim the girl had burned pages of the Koran, and we are investigating, and we have not reached any conclusion," he said.
Christians often live in fear that they will be accused of blasphemy, and many critics say the legislation is sometimes used to settle scores.
Angry mobs have been known to sometimes take the law into their own hands and beat or kill people who are accused of violating the blasphemy laws. In July, thousands of people dragged a Pakistani man accused of desecrating the Koran from a police station in the city of Bahawalpur, beat him to death and then set his body on fire.
Attempts to revoke or alter the blasphemy laws have been met with violent opposition, however.
Last year, two prominent Pakistani political figures who spoke out against the laws were killed, in attacks that raised concerns about the rise of religious extremism in Pakistan.
Liberal politician Salman Taseer was shot and killed by one of his own guards in January 2011, and in March 2011, militants gunned down Shahbaz Bhatti, the only Christian minister in Pakistan's Cabinet.