Missing New Yorker's chilling text: "The girl with this phone is dead"

(CBS News) The family of a missing New York woman is extremely worried after they got a chilling text message from her cell number: "The girl with this phone is dead was smiling."

Authorities said 26-year-old Rajwinder Kaur was last seeing in her Queens home Sunday at 8 p.m. when she was on her way to volunteer at a Brooklyn shelter, CBS New York affiliate WCBS reported.

Rajwinder's youngest sister received the mysterious message at 9:40 p.m. ET the night she vanished.

"I was reading it and it didn't make sense and I worried, what's going on?" the youngest sister, Gurpreet, told CBS 2's Sean Hennessey.

"We are very nervous, we are scared, I know Raji. She will never send a message like that," added brother-in-law Kulwinder Bhinder.

Watch: Shocking Text Message Leaves Family Of Missing Queens Woman 'Very Worried'

Kaur's family said they are anxiously waiting answers to what happened to Rajwinder, a social worker who recently became involved in volunteering at shelters. They tried to get the word out on Twitter and Facebook, but still haven't learned any new information.

"Nobody has called. We've even reached out to our community, the Punjabi community, we put like news in the ... Indian [TV] channels and all that and we haven't heard anything from anybody yet," Lucky said. "We're really very, very worried.

Her family did not know what shelter she was heading to and have put missing fliers at dozens of them.

NYPD sources told CBS 2 that Rajwinder had sold some belongings on eBay before she disappeared and believe that she joined a cult. The creepy text could mean "the old Rajwinder is dead to you; the new Rajwinder is with us" the sources told Hennessey.

The Kaur family, however, is skeptical of that theory, describing the 26-year-old as a religious girl who wouldn't do something so extreme. They do, however, believe she is alive.

"Yes, I have to believe that," Gurpreet Kaur said. "We do."

Rajwinder is described as 5-foot-3 and 130 pounds with a thin build and medium complexion. The family is offering a $1,000 reward for information that leads to her safe return.

Anyone with information in regards to this missing is asked to call Crime stoppers at 1-800-577-TIPS (8477). The public can also submit their tips by logging onto the Crime stoppers website at WWW.NYPDCRIMESTOPPERS.COM or by texting their tips to 274637 (CRIMES) then enter TIP577.