Las Cruces police are warning residents that someone threatened to randomly shoot people if city leaders failed to hand over what they described as a "substantial" ransom.

The city received the second of two threatening letters Friday afternoon, but police remained tightlipped about details of the demand, including how much money was involved. They did say the demand called for a "substantial amount."

At a news conference late Friday, Lt. Randy Lara said he didn't want to alarm residents but he urged them to watch for any suspicious activity.

"The letter did reference that Las Cruces residents will be shot at random if the city didn't comply with the extortion," Lara said.

The letter — the second sent to the city in recent weeks — was hand written with an unusual style of printing.

Las Cruces police activated extra resources, and the FBI, state police and Dona Ana County Sheriff's Office were helping with the investigation.

City, state and federal law enforcement were taking the threat seriously, Lara said, adding that law enforcement would be on heightened alert for an indefinite period.

"We are prepared to do whatever it takes to keep citizens safe," he said.

The decision to tell residents about the threat was weighed against the possibility of unnecessarily alarming residents.

"It has gotten to the point that it's more desirable that the public knows," Lara said. "It's better to have 80,000 pairs of eyes on this person or persons."