LANSING, Mich. (WLNS) — Strange Matter Coffee Co. decided to close its doors Tuesday after receiving a strange letter.

The coffee shop announced the decision with a sign on the front door Tuesday morning that said they were temporarily closed.

“Out of an abundance of caution, we’ll be closed for a few days while the FBI and LPD investigate a credible threatening letter we received,” the sign at Strange Matter said.

Lansing Police spokesperson Jordan Gulkis confirmed with 6 News they are investigating the incident, along with the FBI.

The threatening letters were sent to some coffee shops in Lansing and Detroit as well. Inside the letter, there was hate speech, vague bomb threats, and more.

Strange Matter Coffee said the letter contained nondescript threats and hateful imagery.

Co-owner Elaine Barr said she decided to close up shop for the next few days after reading all 10 pages.

“There were a few swastikas, but also some general nonsense,” Barr said.

The Gathering Coffee Co. in Detroit and 517 Coffee Company in Lansing also received threats.

“There were bombings of planes bombing power plants, stuff about Russia having Nazi’s in our country already, dates on when Russia was gonna bomb U.S. power plants,” said James Defrees, co-owner of 517 Coffee Company.

Defrees says they got the letter on Feb. 16.

The FBI sent 6 News a statement that said the threats received in Lansing and Detroit will be taken very seriously, and it encourages the public to report suspicious activities that could present a threat. However, Barr says it is concerning that these threats were sent to multiple coffee shops.

Strange Matter says it will re-open when they feel it’s safe, and will work to pay employees for the shifts they missed.

In a post on Instagram, Strange Matter shared more details about why they made the decision to close.

6 News has obtained a copy of the letter, which contains a series of random handwritten notes, numbers, and other scribblings, but did not appear to have any specific threats to Strange Matter Coffee Co.