A day before the Trump administration was set to conduct mass roundups of undocumented immigrants around the U.S., a man threw incendiary devices at an immigrant detention center in Washington state and was later found dead at the scene after police opened fire.

A man identified by authorities as Willem Van Spronsen, 69, of Vashon Island had set a vehicle outside the Tacoma Northwest Detention Center on fire and attempted to ignite a large propane tank next to the building, police said.

He was armed with a rifle and had flares, Tacoma police said.

Four officers responded to the incident Saturday morning at 4 a.m. after an employee reported that “a male outside the facility was armed with a rifle,” police said.

Moments later, officers reported that shots had been fired. Spronsen was then found dead.

The shooting took place about six hours after a peaceful rally in front of the detention center, Tacoma Police spokeswoman Loretta Cool said. She said another rally was planned for Saturday afternoon, but it would have to be held in a different location because authorities are still investigating the incident with the man.

The Tacoma Northwest Detention Center contracts with the Department of Homeland Security to house immigrant detainees pending deportation proceedings and has 1,575-beds.

Run by the private company GEO Group, the center has also held parents separated from their children.

After the early morning police-involved shooting, detectives were called into the scene to launch an investigation along with forensics experts.

As the investigation continues, the four Tacoma police officers who fired their weapons have been placed on paid administrative leave per department policy.Spronsen's motive hasn’t been determined, Cool said.