Police Commissioner William Gross and Mayor Marty Walsh said Thursday there's no truth to stories, circulating on Facebook, that Boston has been hit by a wave of vans driven by evil people trying to abduct children or young women.

The stories began spreading about a month ago. People are now posting photos of white vans with out-of-state plates - sometimes with prominent locks on the rear and side doors - from Mt. Vernon and Selden streets in Dorchester to Dudley Square to a mall parking lot on American Legion Highway in Roslindale.

One account claimed a man and woman would approach young women in Dorchester and Mattapan claiming to sell incense, but the substance was really a drug that would knock the women out, letting the couple drag them to their van.

State Rep. Liz Miranda (Roxbury, Dorchester), wrote "there have been many reported missing children and abductions in and around Boston" and provided a series of tips for reducing the odds of children getting kidnapped.

But it's just not true, Gross and Walsh said yesterday.

Gross said police have not found any instances of children being abducted - or of white-van people trying to kidnap kids - over the past month.

Gross said he would be the first to go public if kids were being kidnapped like that, both to alert the public and to seek help capturing suspects.

Gross compared the current reports to a spate of reports in 2016 of roaming armed clowns.

In several of the reports, people who spotted the vans said they called 911 - and that the van drivers departed after police came to investigate them.

Miranda explained why she posted what she did:

"Due to reports online and in community, our neighborhoods are alarmed. I created the list to help parents and citizens to be prepared and to prepare kids if they should experience an incident.

"It was shared 700 times because the community which has a difficult relationship with both police & government ( which now I am among). Media bias and systemic issues make it incredibly hard for our community. As a former youth worker and organizer I know first hand low income, of color, LGBTQIA youth are incredibly vulnerable. Although we don’t want communities falsely alarmed. I want my community prepared. Human trafficking is real and if the community is scared, as their Rep I want to support them. Their issues are mine too."