A 51-year-old woman from Colombia has died and five more people are injured after a Greyhound bus passenger opened fire on six people on the California Interstate 5 Monday.

A total of 43 people were travelling from Los Angeles to the San Francisco Bay Area before 1.27am and one witness said an altercation began after a passenger asked the gunman to be quiet.

'He was, massive, so tall, I remember before this happened, I noticed he had really big shoes on,' passenger Mark Grabban, 29, told NBC News. 'He was muttering things, about "wait till we get to the station".'

Then Grabban heard 'f**k you, f**k all of you'.

The witness added: 'I heard a gun cock, and eight to nine rounds let off.'

Another passenger said that they woke up to the male suspect yelling, 'prompting us further in the back to take cover'.

They said fellow passengers seemingly 'physically subdued' the gunman after shots were fired.

Six people were shot by a fellow Greyhound bus passenger on Monday after 1am. A 51-year-old woman from Colombia died at the scene on the bus and five others were taken to hospital

A witness said an altercation began after someone asked the gunman to be quiet. Investigators are seen outside of a Greyhound bus later on Monday

The driver got the gunman off the bus after pulling over on to the right hard shoulder

The driver was praised by police who said he immediately pulled over on the hard shoulder of the I-5 and persuaded the shooter to get off.

The shooter left the weapon - a black handgun, make and model unknown.

The driver continued to the next exit on Grapevine Road, where victims were able to get medical attention.

Numerous people on the bus made 911 calls and multiple agencies, including the Kern County sheriff's and fire departments, responded to the original scene south of Bakersfield.

California Highway Patrol said a suspect was in custody on Monday by 1.34am. The suspect was taken in without incident.

Five of the victims were taken to hospital with moderate to major injuries. One of those five was airlifted from the area in Tejon Pass, which rises to an elevation of more than 4,100 feet (1,250 meters).

The driver has been praised for driving onto the next exit and getting the victims medical attention

Police said the suspect left the weapon - a black handgun - behind on the bus

The body of the dead woman remained on the bus at 6.30am Monday while others were taken to hospital

Greyhound told DailyMail.com in a statement: 'Our thoughts and prayers go out to everyone and every family member impacted by the incident today'

However the fatally injured body of a woman from Colombia remained on the bus, 80 miles northwest of LA, around 6.30am local time.

Sgt. Brian Pennings said the driver 'handled the situation professionally and appropriately to minimize any more possible victims'.

'We’re grateful that the bus driver acted quickly,' Pennings added. 'His actions were very appropriate and one could say heroic.'

The identities, ages and genders of the victims were not immediately known.

Police sealed off a Valero gas station on the 8000 block of Grapevine Road East near Lebec and the on and off ramps to the section of the freeway were closed around 3am.

Police were waiting to interview the suspect Monday morning.

Sgt. Brian Pennings added that an incident like this is rare and he's never seen anything like it in his 25-year career.

Greyhound told DailyMail.com in a statement: 'Our thoughts and prayers go out to everyone and every family member impacted by the incident today.

'We are gathering details and will assist the Kern County police in every way possible during their investigation. What we do know at this time is that the incident involved schedule 6848-1, traveling from Los Angeles to San Francisco.'

Forty people were on the bus going from LA to the San Francisco Bay Area. Passengers were shaken and angry

One passenger said they woke up to the male shooting yelling and 'prompting us further in the back to take cover'

One woman who appears to suffer from PTSD after the October 2017 Las Vegas mass shooting, woke up to a man yelling and thought she was going to die

Passengers, who were scheduled to be dropped off in San Francisco and Oakland, were shaken and angry.

One tweeted Greyhound: 'You need to implement proper security measures at ALL of your stations! A bus departing from Los Angeles had been infiltrated by someone with a gun, and we are currently stopped at the Grapevine to have authorities and paramedics assist with the shooter situation!'

The social media user who had missed their intended bus and had to get on a later one, said at the time of the shooting 'the lights were off due to the nature of it being a red-eye overnight ride'.

The passenger said they were about 'half the bus' length away from where the incident had occurred' and 'was unable to identify the suspect outside of him being male' but 'from what I can tell, some passengers physically subdued him'.

They added in tweets: 'Until Greyhound and Megabus implement proper security measures, I am either flying or hitching a ride with a friend or other trusted person for future SoCal trips! As of now, I no longer feel safe using these services!

'A transportation service that allows for people to bring weapons on board is not a transportation service worth using.'

Police said the suspect was arrested without incident and used a black handgun, make and model unknown. Sgt. Brian Pennings is pictured

Another passenger who appears to suffer from PTSD after the October 2017 Las Vegas mass shooting, woke up to a man yelling and thought she was going to die.

‘I’m okay. Just was on my way to San Francisco shooting happened on the Greyhound,' she posted on Twitter.

'I suffer from Vegas tragic couple years and I was asleep [sic] and a guy talking so loud and started firing 7-9 round and happened so fast I thought that was the end.’

Passengers had to wait for a rescue bus to collect them after the incident so they could continue their journey.

Grabban, who heard the altercation break out, said that Greyhound needs to screen passengers using metal detectors like they would at an airport.

The British man who lives in the States was with with his girlfriend and says he told a mother who was with her young children to stay crouched down.

Grabban said the shell casing from one of the bullets landed on his lap.

'I dove to the floor right to under the seat, I got to my girlfriend, tried to put her head down. I was just waiting for the next shot, I was assuming I was going to get shot,' Grabban added to NBC News.

'I saw the blood on the floor of the aisle. I looked to the woman on the left, and she wasn’t responding, wasn’t moving or anything. She was lifeless. It was horrifying to see. I hadn’t seen anything like it.'