Investigators turned their attention to south Florida Thursday evening in the hunt for the bomber who has mailed 10 explosive devices to prominent Democrats and Trump critics in the past five days.

A Miami-Dade Police bomb squad and a K-9 unit joined federal investigators Thursday to examine a U.S. mail distribution center at Opa-Locka, northwest of Miami.

The department later tweeted that it was assisting the FBI “as a precautionary measure,” but could not “provide additional information at this time due to the active nature of this federal investigation.”

Homeland Security Secretary Kirstjen Nielsen confirmed the shifting focus to the Sunshine State, telling Fox News: “Some of the packages went through the mail. They originated, some of them, from Florida.”

Investigators will mine cell tower data from areas in Florida they believe packages were sent from to identify phone numbers and ultimately users who were in the vicinity at the time, officials told the New York Times.

Suspicious packages have so far been sent to liberal donor George Soros, former President Bill Clinton and his wife, former Secretary of State Hillary Clinton, former President Barack Obama, former Attorney General Eric Holder, former CIA Director John Brennan (via CNN) and actor Robert De Niro. Rep. Maxine Waters and former Vice President Joe Biden were each sent two devices.

Most packages were sent through the mail system, but some were delivered directly. The devices sent to CNN and De Niro's Tribeca Grill restaurant, both in New York, were reportedly dropped off by a courier. The package sent to Soros was placed directly in his mailbox.

All the packages had one thing in common: the return address was the office of Rep. Debbie Wasserman Schultz’s in Sunrise, Florida.

A member of the New York Police Department walks with a bomb sniffing canine outside the Time Warner Center after a suspicious package was found inside the CNN Headquarters in Manhattan, New York, U.S., October 24, 2018. (REUTERS/Shannon Stapleton)

Though unsophisticated, the bombs are being treated as “live devices,” according to New York City police commissioner James O’Neill.

“The devices should be considered dangerous,” he warned, during a press conference Thursday.

The packages contained pipe bombs, about six inches long, with some combination of powder, wires and a battery. The device sent to CNN also contained glass shrapnel.

The basic designs could have been lifted from “The Anarchist Cookbook,” a notorious bomb and hacker manual dating to the early 1970s, according to one official speaking to Reuters.

The bombs are being treated by authorities as an act of domestic terrorism.

Reflecting on the bomb scares, President Donald Trump called for “all sides to come together in peace and harmony” at a Wednesday rally in Wisconsin. However, in the days since he has tried to blame the media bringing about the crisis.

He called for the mainstream media to “clean up it’s act Thursday on Twitter, and hit out again Friday, slamming the press for “ridiculously comparing this to September 11th and the Oklahoma City bombing.”