Nassau says it accidentally sent out a robocall Monday night to all homeowners in the county.

The call said if they didn't apply for their senior tax exemption by Jan. 1, they would lose it. The call was only supposed to be sent to about 3,500 people who would be affected.

"Hi, this is Nassau County Executive Laura Curran. Records with the department of assessment show that you have not yet submitted your application for the senior exemption for the 2019-2020 tax year," the robocall said.

On Tuesday, the county’s assessment office was flooded by concerned residents. The line snaked around a corner and even outside into the cold. Many people said the error made them livid, and Curran apologized for the mistake.

"I understand that this has caused a lot of anxiety and a lot of anger, and I really apologize to our seniors for this error of the robocall system," Curran said.

After hours of long lines and visible frustration, Curran came down and spoke to residents about the error. She said a second robocall went out to residents clarifying and explaining the mistake.

The Jan. 1 deadline for those who were supposed to get the initial call has been extended.

News 12 is told that 800 people signed into the assessment office on Tuesday. Of them, 300 were able to finish the paperwork for the exemption.

Rich Nicolello, the presiding officer of the Nassau County Legislature, was assessing the situation earlier Tuesday. He called it "pure incompetence."