Dallas police believe the shooter responsible for the deaths of five officers was planning a bigger attack.

"We are not going to let a coward who would ambush our police officers change our democracy," Dallas Police Chief David Brown told reporters.

SEE MORE: These Are The Victims Of The Dallas Protest Shooting

Authorities say the suspect — identified as Micah Johnson, a member of the Army Reserve for six years — was planning to attack police on a larger scale but fast-tracked those plans after the recent police shootings of two black men in Minnesota and Louisiana.

Click through images from protests over Alton Sterling, Philando Castile shootings:

19 PHOTOS Protests around country over Alton Sterling, Philando Castile shootings See Gallery Protests around country over Alton Sterling, Philando Castile shootings ST. PAUL, MN - JULY 09: Protestors yell at police from a bridge on July 9, 2016 in St. Paul, Minnesota. A protest shut down highway I-94 during a march to commemorate Philando Castile who was killed by police on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Police officers launch smoke bombs and tear gas to clear out protestors who shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Police officers line up to clear out protestors who shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Police officers launch smoke bombs and tear gas to clear out protestors who shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) BATON ROUGE, LA -JULY 09: Protesters lock arms and shout at law enforcement in riot gear on July 9, 2016 in Baton Rouge, Louisiana. Alton Sterling was shot by a police officer in front of the Triple S Food Mart in Baton Rouge on July 5th, leading the Department of Justice to open a civil rights investigation. (Photo by Mark Wallheiser/Getty Images) ST. PAUL, MN - JULY 09: Protestors shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) BATON ROUGE, LA -JULY 09: Baton Rouge police removed protesters that were arrested on July 9, 2016 in Baton Rouge, Louisiana. Alton Sterling was shot by a police officer in front of the Triple S Food Mart in Baton Rouge on July 5th, leading the Department of Justice to open a civil rights investigation. (Photo by Mark Wallheiser/Getty Images) ST. PAUL, MN - JULY 09: A protestor is held back by another man on shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have happened every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Protestors shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Ph22oto by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: A protestor raises his fist on shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Police line up as protestors shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: A police officer gives commands as protestors shut down highway I-94 on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) ST. PAUL, MN - JULY 09: Protestors raise their hands as police attempt to move them off highway I-94 which they shut down on July 9, 2016 in St. Paul, Minnesota. Protests and marches have occurred every day since the police killing of Philando Castile on June 6, 2016 in Falcon Heights, Minnesota. (Photo by Stephen Maturen/Getty Images) Protestors shout slogans during a protest in Times Square in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) Police officers stand guard during a protest in Times Square in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) Police officers stand guard during a protest in Times Square in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) People shout slogans during a protest in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) A protestor shouts slogans during a protest in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) People gather in Union Square during a protest in support of the Black lives matter movement in New York on July 09, 2016. The gunman behind a sniper-style attack in Dallas was an Army veteran and loner driven to exact revenge on white officers after the recent deaths of two black men at the hands of police, authorities have said. Micah Johnson, 25, had no criminal history, Dallas police said in a statement. / AFP / KENA BETANCUR (Photo credit should read KENA BETANCUR/AFP/Getty Images) Up Next See Gallery Discover More Like This HIDE CAPTION SHOW CAPTION of SEE ALL BACK TO SLIDE

A source told WFAA, "We think he was probably planning something bigger based on what we found at the house with the explosive materials."

Police say Johnson didn't have any explosives built, but he had plenty of materials to create pipe bombs.

Protests were triggered around the country last week after the officer-involved shooting deaths of Philando Castile and Alton Sterling. WFAA's report said the shooter knew police would be out in full-force at protests in Dallas.

Police reportedly found an arsenal of weapons amassed by the shooter when searching his home. They say he "wanted to kill white people, especially white officers."

"This was a mobile shooter that had a written manifesto on shooting and moving. He did his damage. We did damage to him as well," Dallas Mayor Mike Rawlings said.

Authorities say he didn't have any ties to terrorist organizations or a criminal record. The investigation into the shooting is ongoing.

This video includes clips from ABC and images from Getty Images.

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