Tensions between Hamas and Fatah were high on Saturday in anticipation of Hamas celebrations of its establishment 20 years ago. Fatah banned Hamas protests in the West Bank. The celebrations come a day after Hamas gunmen burst into the Gaza home of top Fatah official Omar Al-Ghoul and arrested him. He was the most senior Fatah politician to be detained since Hamas forces overtook the territory in June. Also Friday, three people were killed in an unexplained explosion at a funeral in Gaza City. Witnesses said a man carrying explosives in a jacket accidentally detonated them, while Hamas security said a member of the procession threw a pipe bomb. Ghoul, arrested by Hamas for "illegal activities," had been spending much of his time in the West Bank after Hamas violently seized control of Gaza last June. He arrived in Gaza on Thursday to attend his mother-in-law's funeral. Al-Ghoul is an adviser to Palestinian Authority Prime Minister Saalam Fayad. Around 4 a.m., armed gunmen in civilian clothes burst into Al-Ghoul's home, ransacking it and seizing him, his relatives said. His wife, Shifa Al-Ghoul, said the gunmen threatened to blow open the door before the family let them in. After 10 gunmen took her husband away, another group searched the home for two hours, she said. The forces confiscated two computers and other personal belongings and abused her verbally before they left, she said. "We still don't know where he is," she said. "They treated me in a barbaric way ... and threatened me with guns a few times." Al-Ghoul is considered a harsh critic of Hamas and frequently attacks the fundamentalists in a newspaper column he writes. The information minister of the West Bank government, Riad Malki, called the arrest "barbaric," saying it was part of Hamas' attempts to "extort" his government. Al-Ghoul's family and supporters later held a protest outside the family home to demand his release. After Hamas took over Gaza, the group's militants detained several prominent Fatah members. At the Gaza City funeral, hundreds of Fatah supporters marched in a procession for one their members who was killed in an IAF airstrike. Witnesses said a participant accidentally detonated explosives he was carrying in his jacket. Standing on top of a moving car with a loud speaker, the man opened up the jacket to show off the explosives and then jumped off the car, triggering the explosion and instantly killing himself and the others, witnesses said. Hamas security officials offered a differing version of events, saying a funeral-goer threw a pipe bomb from the procession, and it bounced off a wall and exploded. The West Bank government allied with Fatah accused Hamas of throwing a bomb at the procession and consequently declared Saturday a national "mourning day." Fatah officials said in a statement posted on the official WAFA news agency that the bombing was a "continuation of Hamas crimes since its coup." Hamas security officials denied their forces were involved. "Fatah is making use of innocent Palestinian blood in a cheap manner to falsely claim that it was Hamas that attacked the procession with bombs," Hamas spokesman Sami Abu Zuhri said.