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NORTH TEXAS (CBSDFW.COM) – Today begins another somber day in Dallas. The first of five funerals will be held for police officers shot and killed in an ambush last week – in total there will be three services, held in Dallas, Farmers Branch and Plano.

Overnight, police officers guarded the doors at Mary Immaculate Catholic Church in Farmers Branch. The location is where a private service will be held for Dallas police Sergeant Michael J. Smith.

Mary Immaculate is Smith’s family church. His children attend Mary Immaculate Catholic School and his wife teaches 4th grade there.

Smith was a U.S. Army veteran and had been a police officer with the Dallas Police Department for 28 years. A public service for Smith will take place Thursday at Watermark Church in Dallas, where he worked security.

Also today, a memorial for Dallas Area Rapid Transit (DART) Officer Brent Thompson will be held at The Potter’s House Church in Dallas. The Wednesday service will honor Thompson — the first ever DART officer to be killed in the line of duty. A private funeral and burial will later be held for Thompson in Corsicana.

Officer Thompson was 43-years-old and had just gotten married a few weeks ago.

The last of the funerals to be held today will remember Dallas police Senior Corporal Lorne Ahrens.

Ahrens, a husband and father to two children, was a towering man who stood 6’5”. Friends say he was “a big man – with an even bigger heart”.

The service for the 14-year DPD veteran will be held at Prestonwood Baptist Church in Plano.

Funerals for the other policemen killed in the ambush, Officer Michael Krol and Officer Patrick Zamarripa, will be held on Friday and Saturday respectively.

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