At least 18 infants and toddlers under two years old were separated from their parents as a result of the Trump administration’s family separation policy, and subsequently kept separated for weeks or months, according to a House Oversight Committee report on the policy released Friday.

Of that, nine children were younger than one year old, the report found. It based its findings on existing records from the “Ms. L” lawsuit — which eventually led a judge to stop systematic separations last year — as well as administrative data from various executive branch agencies.

One child included in the Ms. L lawsuit class, the youngest on record, was four months old at the time of separation. The New York Times reported on the child, Constantin Mutu, last month.

Another child, an eight-month-old from Honduras, was separated from his father and sent to a facility under the purview of the Department of Health and Human Services’ Office of Refugee Resettlement for nearly six months.

“At the time of his release, the baby had spent nearly half of his life without his parents, in the custody of the Trump Administration,” the report stated. “It is unclear whether the child and father have been reunited.”

The full number of separated infants and toddlers may well be much larger, the report acknowledged. It did not address potentially thousands of children separated from their parents before the Trump administration went public with its “zero tolerance” prosecution initiative in April last year. It also didn’t account for any children separated after a federal judge intervened in the matter a few months later, in June.

That “zero tolerance” initiative, the legal basis for the separation policy, meant that everyone arrested while crossing the border, even parents with children, was systematically charged with at least misdemeanor illegal entry. Because children cannot be held in criminal detention, they were considered “unaccompanied” and separated from their parents as a result.

In some cases, the report found, the criminal justice process took just a day or two — because parents were sentenced to time served, or because prosecutors declined to charge them at all — but, nonetheless, adults returned to holding facilities to find that their children had already been reclassified as “unaccompanied” and sent elsewhere.

In one case, for example, a 13-year-old Guatemalan boy and his father were arrested at the border on June 11 and sent to a Border Patrol facility. On June 12, the father was briefly transferred to U.S. Marshals’ custody before being returned to the Border Patrol facility, only to find that his son had already been transferred elsewhere.

It took more than a month for father and son to reunite, the report said. In some cases like these, a DHS official told investigators last year, families weren’t immediately reunited because doing so would have required extra paperwork.