A driver for the smugglers in Dahriya who spoke on the condition that he be identified only as Abu Ramzi said that he and his colleagues alert Palestinian security forces at the first hint that a client intends to commit violence in Israel. He complained that the Israeli military had stepped up patrols of the southern barrier since the Tel Aviv shootings.

“Before this last attack, the army would act as if nothing was going on — 30 or 40 workers would cross into Israel all at once,” said Abu Ramzi, 34. “This last attack has temporarily complicated our operation.” Still, he said, “we will always find ways to get these workers in.”

That resolve was tested after nightfall last Monday, when five pickups and a Mazda sedan filled with workers massed in the center of Dahriya. With their lights off, the vehicles made two attempts to cross the web of rutted, rocky dirt roads and reach gaps in the fence, but they turned back because spotters saw Israeli Army Humvees converging on the same areas.

Finally, the smugglers’ vehicles roared toward another spot, throwing up thick billows of dust and bouncing the workers mercilessly in the beds of the trucks. At the bottom of the hill, two lookouts were talking on their cellphones under an olive tree. To the west, past the fence, nothing was visible but the distant lights of Israeli towns and cities.

Then the lights of the cars sent to pick up the workers on the Israeli side could be seen approaching on the bare hills. A smuggler yelled, “Yalla, yalla!” — “Go, go!” — and workers leapt from the trucks and began running toward a gap in the fence that had been flimsily repaired. Someone pulled it open, and someone else carefully lifted a few strands of razor wire that had been tossed in the dirt to make the passage more difficult.

The workers, many toting backpacks stuffed with clothing, slid under the razor wire and met the cars. The last man lifted the razor wire himself, slipped under and ran toward the cars, which drove off toward job sites among the distant lights.