Jerusalem ? With sirens wailing and blue lights flashing, Israeli police chased a van with explosives on a main highway Tuesday and captured a group of Palestinians who defense officials say planned a major bombing ahead of national elections.

Israel’s parliamentary election is set for March 28; Palestinian attacks have altered the outcome of past balloting.

After chasing the group halfway from Jerusalem to Tel Aviv, security forces extended a closure on the West Bank and Gaza through election day.

AP Television News video showed the 10 Palestinians removed from the van at gunpoint, stripped to their underwear, and forced to lie face down in a field next to the highway, arms extended. Demolition experts took away a 15-pound bomb, concealed in a bag.

Jerusalem police commander Ilan Franco said the suspected bomber in the group had ties to the militant group Islamic Jihad. Authorities said he planned to blow himself up in central Israel, without pinpointing the location.