A couple accused of kidnapping two young Amish sisters were prowling for easy targets and may have also planned to abduct other children, a sheriff said Saturday.

Stephen Howells Jr. and Nicole Vaisey, both of Hermon, were arrested Friday on charges they snatched the seven-year-old and 12-year-old girls from a roadside farm stand in front of their home near the Canadian border.

St. Lawrence County Sheriff Kevin Wells said at a news conference Saturday that investigators are looking into whether the pair had plotted or carried out other abductions.

"We felt that there was the definite potential that there was going to be other victims," Wells said.

The sisters were abducted Wednesday from their family's farm stand in Oswegatchie and were set free by their captors Thursday.

Howells and Vaisey were arraigned late Friday on charges of first-degree kidnapping with the intent to physically harm or sexually abuse the victims.

The sheriff said Howells, 39, and Vaisey, 25, "were targeting opportunities" and did not necessarily grab the girls because they were Amish.

"There was a lot of thought process that went into this," Wells said. "They were looking for opportunities to victimize."

The suspects are being held without bail and have a preliminary court appearance scheduled for Thursday.

Bradford Riendeau, a lawyer for Vaisey, said, "We're going to be reviewing the available evidence." He expects to speak with her in jail later Saturday, he said.

There was no answer Saturday at the offices of the St. Lawrence County Conflict Defender's Office, which is representing Howells.

Wells said the girls were able to provide details to investigators about their time in captivity.

The Associated Press generally does not identify people who may be victims of sexual abuse.

Two girls who were taken from a farming community in Oswegatchie, were found at the door of a house in Hermon. (CBC)

The St. Lawrence County Sheriff's Office issued a statement late Friday saying the arrests of Howells and Vaisey "no doubt saved young children from future abuse."

Wells said in a statement that the older of the two girls provided "crucial information" that led to the arrests.

District Attorney Mary Rain said information provided by the girls helped lead to Howells and Vaisey. The suspects' home is about 21 kilometres from where the girls live.

"The suspects agreed to go to the sheriff's office to be interviewed earlier today and they were arrested after those interviews," Rain said.

The Associated Press generally does not identify victims of alleged sexual abuse.

Some families take down their stands

The seven-year-old and 12-year-old vanished Wednesday evening in Oswegatchie, touching off a massive search in the farming community near the Canadian border.

They turned up safe about 24 hours later at the door of a house about 24 kilometres from where they were taken. Hermon is about 21 kilometres from Oswegatchie.

Searchers had scoured the farming community of about 4,000 people, in a hunt hampered by a lack of photos of the girls for authorities to circulate.

This has sent a shockwave through their community. - Patricia Ritchie, state senator representing the region

The Amish typically avoid modern technology, and the family had to work with an artist who spoke their language, a German dialect known as Pennsylvania Dutch, to produce a sketch of the older girl.

The episode left a sense of vulnerability in a community where residents said even small children often walk unaccompanied to school.

"One thing that comes from this is that people learn this can happen in a small town," the prosecutor said. "I think the public will take precautions, and that's the sad thing."

Patricia Ritchie, the state senator representing the region, said many are now reluctant to let their children play outdoors unattended.

Ritchie said the Amish are responding in a way that may forever change a familiar feature of the local landscape: Some are taking down their roadside stands.

"This has sent a shockwave through their community," she said.