NEW YORK (NYTIMES) - Seven British citizens said they were vacationing in Canada when they had to swerve to avoid an animal, not an uncommon occurrence in rural British Columbia. But doing that proved dangerous in its own way.

They had turned off the road into the United States, across an international border.

Border Patrol officials detained the two couples and their three young children, who were held in American custody for nearly two weeks. They were deported on Wednesday (Oct 16) after spending the past 11 nights in a Pennsylvania detention centre, said a lawyer for the families.

"This is how the scariest experience of our entire lives started," Mrs Eileen Connors, one of the detained Britons, wrote in a sworn statement filed to the inspector general of the Department of Homeland Security. "We will never forget; we will be traumatised for the rest of our lives by what the United States government has done to us."

According to Mrs Connors, her husband David and his cousin were arrested despite their protests that they did not intend to cross the border. They asked if they could turn around, she wrote, but the officer said they would all be held.

A spokesman for the US Customs and Border Protection said on Tuesday that the vehicle was seen on surveillance video on Avenue 0 in British Columbia at about 9pm on Oct 2.

The official said the vehicle then crossed the border "by slowly and deliberately driving through a ditch onto Boundary Road in Lynden, Washington".

Fifteen minutes later, the driver and six passengers - including two-year-old twins and a three-month-old - were arrested. The spokesman said record checks showed that two of the four adults had been denied travel authorisation to the US.

Canada refused to allow their return, the spokesman said, and the British Consulate could not be reached. Mrs Connors said they had a visa waiver, which entitled them to travel to the US for business or tourism for stays of up to 90 days without a visa, although they were not aiming to visit the US that night.

"They didn't want to be here," said their lawyer, Ms Bridget Cambria. "This is the only family that has come from across the border who wants to leave. Normally, people who want to come to the United States are in this facility."

On their first night in detention, Mrs Connors wrote, she and her baby were kept in "a very cold" female-only cell at a Customs and Border Protection facility in Washington. She put her three-month-old son on top of her and tried to rest.

"It was futile because he kept sliding off of me, and I just could not let him lie on the disgusting floor," she wrote.

Immigration officers told them the next day that they would be released if they provided contact information for a family member in the US who could become their sponsor, she said. But after they gave the name of a relative, she wrote, immigration officials said there was a change in plans.

They were turned over to Immigration and Customs Enforcement, wrote Mrs Connors, 24. Mr David Connors, 30, was dropped off at the Tacoma Northwest Detention Centre, while she and her son were taken to a Red Roof Inn in Seattle.

Ms Cambria said they were in customs custody for a much shorter period then most border crossers. "They had an understanding of the language and their rights and were outspoken," she said, adding that many others do not have the same luxury.

The next morning they were put on a flight to Pennsylvania, where they were taken to the Berks Family Residential Centre in rural Leesport, she wrote. The other adults and their infant twins were taken to the same place, Ms Cambria said.

The baby had not completed his immunisations, making him especially vulnerable to germs and contagious diseases, she wrote in a letter to Homeland Security, adding that he had not yet seen a paediatrician.

"We all had to shower when we arrived, but because he is too small to take into a shower, I had to wash him off in the office on a sofa, using a washcloth and soap that I had with me," Mrs Connors wrote in her sworn statement. "They offered me a baby bathtub to use, but it was filthy dirty and had broken bits, so I refused to use it."

She wrote that the temperature dropped to 10 deg C at night and that the staff refused to turn the heater on.

The baby woke up with a swollen, teary eye, and his skin was rough and blotchy, she wrote.

Officials did offer to remove the baby, she wrote: "If we wanted, we could sign papers to allow him to be separated from us and taken to some other facility."

Immigration and Customs Enforcement officials did not return a request for comment. About 4,300 people were arrested at the Canadian border in 2018, and about 3,000 in 2017.

There are eight families with children under the age of five being held at the Berks centre, said Ms Jasmine Rivera, a community organiser who is the coordinator for the Shut Down Berks Coalition. The centre is run by the county under a contract with Immigration and Customs Enforcement and houses about 90 parents and children.

"It is undoubtedly the worst experience we have ever lived through," Mrs Connors wrote. "No one should have to suffer this kind of treatment. This would never happen in the United Kingdom to US citizens, or anyone else, because people there are treated with dignity."