A protest organiser in Pakistan has been arrested for leading demonstrations demanding government action after the massacre of seven Christians at a Karachi charity.
Baseer Naveed was taken into custody on Thursday and held overnight at a police station in the southern city of Karachi where the killings took place two days earlier.
Police say he was detained for activities which threatened peace and order.
Meanwhile, Christian groups are holding a second of three days of mourning for the victims of the attack.
Police have so far arrested no-one in connection with the killings, but suspect militants angry at the US-led war on terror are to blame.
"This is strange. The killers are at large but those protesting are being detained," Mr Naveed, a Muslim, told The Associated Press news agency from his cell.
Execution
On Friday, Pakistani President Pervez Musharraf said the killings were an attempt to destabilise Pakistan.
General Musharraf also said the authorities were investigating the possible involvement of India's intelligence agency, known as the Research and Analysis Wing (RAW), in the killings.
Police have been questioning one of two survivors of Wednesday's execution-style attack. One other is in a critical condition.
Two gunmen entered the third-floor offices of the Institute for Peace and Justice (IPJ) and shot their victims in the head, before escaping.
Police said the victims had their hands tied and their mouths had been covered with tape.
Officials are investigating possible links between the killings and a string of attacks on Christian and Western targets that have taken place in the country in recent months.
Police are also looking at a possible link with the mysterious murder of the charity's former chairman four months ago.
He was found dead in his office after being injected with poison.
Black flags
Pakistani Christian groups say they are not reassured by government pledges to protect them following Wednesday's attack, and are being increasingly victimised because of US policy.
Black flags are flying over churches and Christian areas in Karachi for a second consecutive day as protests continue at the latest killings.
Shops, schools and churches in Christian-dominated districts are also closed.
Non-Muslim organisations say recent attacks show that hardline Islamists are trying to force Christians to leave the country.
Karachi was the scene of an attack on the US consulate in June and a suicide bombing against French naval engineers in May.
· 9 Aug - five nurses die in missionary hopital attack in Taxila
· 5 Aug - six dead in missionary school attack in Murree
· 14 June - 11 killed in bomb attack outside US Karachi mission
· 8 May - Karachi bus blast kills 15
· 17 March - five killed in Islamabad church grenade blast
· October 2001 - 18 killed in Punjab church attack