Kabul ? A suicide car bomber struck near the front gate of NATO headquarters in Kabul on Saturday, killing seven people and wounding nearly 100 in a brazen daylight attack less than a week before Afghanistan’s landmark presidential election.

Also Saturday, U.S. Marines pushed deeper into the strategic Helmand province town of Dahaneh for a fourth straight day, meeting fierce Taliban resistance as surface-to-surface missiles and Harrier fighter jets pounded insurgent positions in the surrounding hills.

The blast, which occurred about 8:35 a.m. in Kabul’s heavily guarded diplomatic quarter, appeared aimed at frightening Afghans against participating in Thursday’s presidential election and demonstrating that insurgents can strike whenever and wherever they want.

A Taliban spokesman claimed responsibility for the explosion, which rattled windows across a wide area of the Afghan capital and sent a huge, mushroom cloud of dense black smoke rising into the blue sky.

It was the biggest insurgent attack in Kabul in six months and shook public confidence in the extensive network of checkpoints and armed guards that maintain security in the city.

The bomber managed to evade several rings of Afghan police and detonated his vehicle about 30 yards from the main entrance to the NATO base, where top U.S. commander Gen. Stanley McChrystal has his headquarters. It was unknown whether McChrystal was there at the time of the attack.