The email, details as part of a police affidavit, was allegedly sent by the suspect, Richard Klementovich, to his estranged wife.
According to the affidavit, Klementovich apologizes to his wife for personal shortcomings, informed her he was on steriods, and mentions dying several times.
It reads, in part:
"I get angry. Angry at this job and law enforcement, and it's them who I will take my anger out on. They will to the job I couldn't and take my life."
"I hope whomever comes to our house is ready to die tomorrow because I will be."
The 42-year-old Klementovich is an 18 year veteran of the Clifton, New Jersey police force. He was arraigned on more than 80 charges early Monday morning, including attempted criminal homicide.
The incident began when the Doylestown Police Department was dispatched for a "neighbor dispute" at 25 Bittersweet Drive at 1:44 p.m. Sunday.
Police say Klementovich initially called the police himself saying there was a civil dispute. When the officer arrived there was an envelope in the driveway addressed to Doylestown police.
"Officer read the note, flipped it over, and it basically stated to the effect that [Klementovich] had 2,000 rounds of ammunition in the home and he is a police officer," said Acting Chief Dean Logan.
The officer left the driveway and went back to his police car. That's when the shooting started.
Police say over the course of hours Klementovich kept firing, 118 shots in all, hitting his target every time.
Two squad cars were riddled with bullets and an armored personnel vehicle was also struck, police said. According to police radio transmissions, the gunman shot out the tires on the armored truck and its vehicle camera.
Authorities say Doylestown Officer William Doucette was injured by flying concrete when a bullet struck the sidewalk. He was not seriously hurt.
Authorities say Klementovich showed up at his estranged wife's house with an arsenal, including high powered rifles and assault weapons.
Neighbors said he and his wife, who have two children, were going through a bitter divorce. They were located in New Jersey safe and sound.
During the barricade situation, neighbors were evacuated, while other residents were told to stay put.
David Boerner's wife and two sons were texting him from their basement while David remained stranded blocks away.
"Right now they have her in the basement with my two sons and all she hears is gunshots and movement on the deck, but no information, so she's rather scared," Boerner said Sunday evening.
County and State Police SWAT teams, along with emergency vehicles from Central Bucks Response Team representing 21 police departments, were in place throughout the afternoon and evening as gunshots echoed through the neighborhood.
Members of the Clifton police force were also called to the scene.
Authorities have been at the home before for domestic disputes. Sarah O'Hara babysat for the children Saturday morning.
"It hasn't really been a normal situation there, I don't think. They've been separated more than once, I believe," O'Hara said.