TULSA, Oklahoma - Tulsa Police are looking for a man they say killed his wife and caused an overnight standoff.

They identify the suspect as Derrick Todd, 52.

Tulsa Public Schools says Todd is employed by the district as a security guard. It released the following statement:

"We are taking all necessary precautions to ensure the safety of our students, teachers, and school leaders. Central High School is on modified lockdown with increased Campus Police presence, and we will have increased Campus Police presence at the Mason Building (Education Service Center.) We are also working closely with the Tulsa Police Department to provide whatever supports might be helpful in the ongoing investigation." 

Police said the incident started Tuesday, November 10, 2015 at about 5:30 p.m. when Todd texted several acquaintances that he had just shot his wife, Tonia Todd. The acquaintances included an off-duty Tulsa police officer and a retired Tulsa police officer.

Police went to the Todds' home in the 6800 block of East 79th Street and the standoff began.  The special operations team initially thought Todd still was inside and put the neighborhood on lockdown.

Officers ended the standoff at about 3 a.m. by firing pepper spray and gas into the home. They found the body of Tonia Todd dead from a gunshot wound. Derrick Todd was gone.

We talked to a woman who said every time she saw Todd at Central High School, he always greeted her with a smile. Friends of his said he began sharing some really dark thoughts about a month ago, letting them know he was going through a difficult time. One friend said Todd was upset because his wife was leaving him.

We've also learned police were called out to the Todd home on Monday night because he was believed to be suicidal. TPD said he told them he was just drunk. He was checked out for high blood pressure and intoxication and released after midnight.

Police said the couple owned three cars and one was gone. They believe Todd is in a 2009 Kia Spectra with Oklahoma tag 405FPA.

Derrick Todd's last post on Facebook was two days ago at 5 p.m. and almost sounds like a good bye. 

"...i just want to say it's been fun being on facebook for little while. keep your head and i will catch u on the rebound i'm just tired no problems thing is wrong just my time love and happiness peace to all brothers and sisters."

Police say if you know where he is to call 911.

Tonia Todd is Tulsa's 51st homicide of 2015.