Gunmen opened fire on a funeral in Dera Ismail Khan on Sunday, killing four people and injuring four in what appeared to be a sectarian revenge attack. Police said that four people opened fire at the funeral and that two of them had been arrested, while the search for the others was in progress.The attack at the Sunni funeral of the son of Union Council Dera Dihat No 2 Councilor Muhammad Qasim came a day after the murder of a Shia Gomal University professor. The Shia professorÂ’s murder and funeral attack have prompted riots, with protesters throwing rocks at shops and vehicles and blocking roads with burning tyres. Eyewitnesses said the situation was tense and the army had been called in to patrol sensitive areas. The administration of Dera has also imposed Section 144.