“I don’t know how they are going to stop the first strike,’’ said one T bus driver who, like others who spoke to the Globe on Monday, asked not to be identified because he was not authorized to speak to a reporter.

“How can bus drivers stop from getting assaulted?” another driver said. “They can’t.’’

“It’s concerning to us, but it is not something that happens every day,’’ said Joseph O’Connor, superintendent in chief of the Transit ­Police. “But one assault is too many.”

The latest assault, by more than a dozen teenagers at a bus stop on Columbia Road early Saturday, prompted a strongly worded statement by the president of the Boston Carmen’s Union Local 589 calling on the Legislature to act quickly on a proposed bill that would crack down on people who attack MBTA and other transit workers.

These employees “are often isolated while working in buses, trolleys, and transit stations and are increasingly becoming the target of violence,’’ said John Lee, the union president. “It is well past time for a crackdown on the thugs that target working women and men on any public transit job.”

The bill, crafted by the union and MBTA Transit Police, would allow officers to arrest people if the officers have probable cause to believe the suspects have committed assault and battery on a public employee or health care worker. Currently, officers summoned to the scene of an assault can only hand out a summons to a suspect.

Transit Police detectives spent much of Monday on the hunt for suspects. Detectives canvassed the neighborhood, sought out witnesses, and got images from cameras posted on nearby apartment buildings and businesses, O’Connor said. They also interviewed the driver, an employee since May 2010 who has not been identified.

The attack began around 1 a.m. after a Number 16 bus, which generally has eight to 10 people at that hour, began making its way from Forest Hills to Andrew Square.

The driver stopped at ­Columbia Road in Dorchester, near Geneva Avenue, and he and a female passenger exchanged words over her fare. She threw her paper Charlie Ticket at him, T police said.

Within minutes, 15 to 20 teenagers standing outside swarmed in front of the bus, preventing it from moving. Some stormed inside and began punching, kicking, and taunting the driver, who struggled to defend himself, said T police.

Some threw objects at the bus and tried to pull the driver through a window. The driver activated emergency lights and an alarm to signal that the bus was in trouble. As police ­arrived, the teenagers scattered, leaving a shaken driver with minor injuries.

“We still do not know what occurred to have triggered this act,’’ O’Connor said. “There was some talk with the female with the fare dispute, but as of right now we have not been able to find any nexus between her and the group. And we are still continuing to identify witnesses to determine facts and circumstances of the case.”

More than 1,000 drivers work for the T. The incident rattled operators at two busy bus hubs in Boston on Monday, includ­ing drivers on much busier, and testier, routes.

“This kind of thing happens for stupid reasons,’’ said one driver on a Number 28 bus, which has seen its share of passenger troubles over the years. “We ask for the fare, and people want to fight us. All we are ­doing is our job.”

A driver who has worked for the T for 14 years said he was attacked last week by an unruly passenger. When the driver would not let the man on the bus, he said the man walked over to the driver’s-side window and punched him.

At a stop on the Columbia Road route where Saturday’s ­attack occurred, Cheryl Jones of Dorchester said she has seen trouble before. Sometimes it is people boarding the bus and refus­ing to pay. But sometimes it is worse.

“More should be done to protect drivers and citizens on the bus,” she said. “A couple of days ago, they were shooting outside a bus. They were targeting someone they knew, but there were innocent bystanders.”

Some drivers said they have developed strategies to assess and manage the range of people who board their buses. Some rely on their faith when things get out of hand. Others drive faster in the hopes of getting troublemakers to their destinations — and off the bus — more quickly.

“This kind of thing is always in the back of our minds,’’ said one driver. “If someone shady comes on the bus, you get a little nervous. You try not to think about it.”