Several hundred drivers and assistants have been targeted in recent years
By Dave Lee
BBC World Service
For Guatemala City's bus drivers , going to work could mean risking their lives.
Human rights group Grupo de Apoyo Mutuo (Mutual Support Group) says that so far this year more than 175 of their colleagues have been murdered, many on busy streets, surrounded by traffic.
The killings have been blamed on street gangs involved in extortion and intimidation.
Recently, fear in the community has turned to anger - on 27 November, a riot led to two men and a woman being beaten and burned in public after they were accused of murdering a driver.
"If you don't pay on time they just kill someone," one driver, who wished to remain anonymous, told the BBC World Service's Sarah Grainger.
"They start killing drivers one by one."
The 24-year-old was left paralysed from the waist down after a gang member shot him in the spine.
He now relies on his wife and mother to care for him, and makes his money by selling children's toys in one of the city's most dangerous sectors, Zona 18.
"It was about 7 o clock at night," he remembers.
"It was in the main street. Two men signalled for me to stop for them, so I pulled over.
"And as I was opening the door for them, a kid with a gun appeared and started shooting.
"Thankfully I was only hit once, but the bullet went into my spine."
He was told he could drive again in a modified bus, but he says it's far too dangerous and expensive. He hopes one day to buy a modified taxi so he can drive and make money once again.
The Guatemalan army and police now offer protection for the drivers and passengers, but this security is not always available, and does not cover all the routes.
The killings may act as a distraction from other crimes
Others say there should be a pre-pay system put in place for transport to avoid large amounts of cash on board, but this would require a massive infrastructure change.
So drivers now feel the only way to keep safe is to give in to the gangs' demands.
Groups of drivers will collectively agree to pay the extortionists off. If they pay on time, the drivers say they are then left alone.
But on other routes, if even just one or two drivers resist the intimidation, the gangs will begin the killing.
Aside from money, others fear a motive for the attacks is to create a distraction, forcing police to devote resources into dealing with the murders, allowing drug-traffickers to continue their work.
'God will look after us'
Ingrid Escobar lost her husband in 2007. She's 33 and has two children.
"It was the 3 August. He left early, at half past four in the morning, for his first shift.
"I took my children to school, and it was while I was dropping off my daughter that friends came and told me that he'd been murdered."
Ingrid now faces a daily struggle to feed herself and her children.
"He said he could earn more doing that than as a bricklayer or something else, and we needed the money to run the house and take care of the children.
"We talked about the possibility of him changing jobs. He said 'No, God will look after us'."
Some of the widows of murdered drivers have joined together to form the Association of Drivers' Widows.
The association's work has paid off. The Guatemalan government has now started offering a monthly pension to those affected by the killings, set at $36 (£21) per month, per child.
Last month, 18 widows received their first instalment, and a further 19 families will get money in December. The government hopes that eventually all families left behind by killed bus workers will get this additional income.
For people like Ingrid, the help will come as a much needed boost to their lives.
"Sometimes there's money for food, sometimes there isn't," she says.
"I haven't found a job, but I'm studying so I can get a job and maybe borrow some money to make sure my children stay in school."
For the women with husbands still driving Guatemala City's buses, Ingrid pleads with them to try and find other work for their loved ones.
"They need to understand. They should tell their husbands it's better to get out - they can't keep doing that job. I say that as someone who's lost their husband.
"My husband's murder remains unpunished. They've never caught the person who pulled the trigger."