AVONDALE, Ariz. -- Avondale Police said they're getting close to finding out how a mercury spill happened at Agua Fria high school on Feb. 12.

Officers served three search warrants at Agua Fria School District buildings, including the school district's office, Agua Fria High School, and a school storage building Thursday morning.

They seized thousands of documents and a computer. Police said they're looking for e-mails between district and school officials.

Lt. Dale Nannenga said Agua Fria school officials have provided police few details about how the spill happened.

"We felt at this point it was best for us to seek these search warrants so we were able to achieve the documents that we needed without relying on other people's cooperation," he said.

He said police are investigating whether the school district endangered students and staff.

"From the beginning of the investigation, we felt there was a crime involved already with how the mercury left the campus," he said.

"We felt it was serious enough with 1,700 kids on campus, that the Avondale Police Department needed to get involved to insure that the facts and circumstances surrounding this incident were investigated fairly and impartially," he said.

CBS 5 has been asking questions about how the spill happened for weeks.

Before a school board meeting on Wednesday, Agua Fria Superintendent Dudley Butts and Assistant Superintendent Lexi Cunningham refused to answer questions about how the spill happened.

During the past few weeks, Butts and Cunningham have repeatedly stonewalled our reporter. They even hid from TV cameras and called their attorneys to try to keep us from the school.

Parents like Leslie Lohn said school officials should tell police everything they know about the spill that exposed more than 60 students and staff members to dangerous levels of the toxic metal.

"I think they should be as up front and honest and open about this as possible," she said.

"I'm disappointed that that's not happening. And I really wish that it was," she said.