TAMPA — Authorities seized millions of dollars worth of synthetic marijuana at a Tampa warehouse Wednesday.

The raid was part of a national operation, led by the Drug Enforcement Administration.

In Hillsborough, local and federal officials descended on three warehouses — two just east of Ybor City and one near Tampa International Airport, which deputies searched three months earlier.

At one of the east Tampa warehouses, authorities hauled away between 300 and 400 bales of the designer drug. Most weighed 60 pounds, and deputies estimate each is worth $170,000.

"We're looking at the possibility of seizing millions of dollars of assets here," said Hillsborough sheriff's spokesman Larry McKinnon.

At that site, near 40th Street and Interstate 4 in Tampa, authorities found 47 employees parsing leafy product into individual packages.

Some workers tore off the spooled packaging using the straight edges of Polk County Sheriff's Office promotional rulers.

No one was arrested. The investigation is ongoing, McKinnon said.

At two other locations, DEA agents donned white biohazard suits and gas masks before walking into the warehouses. Synthetic marijuana is sprayed with chemicals, including concentrated acetone, which can burn nostrils and eyes.

A DEA spokesman declined to comment on Wednesday's seizures, saying the agency's work is part of a nationwide investigation and that details will be released Thursday.

The site near the airport — at 6308 Benjamin Road — also was raided in April.

That time, Hillsborough deputies took samples and sent them to the Florida Department of Law Enforcement to find out if they contained any illegal compounds.

Because officials can't outlaw "synthetic marijuana" — only the compounds in it — lawmakers have made it illegal to possesses the most-often used compounds.

However, designer drug-makers tweak the compounds to stay ahead of the law.

Those samples, taken near the airport in April?

Turns out, McKinnon said Wednesday, they were legal.

Jessica Vander Velde can be reached at jvandervelde@tampabay.com or (813) 226-3433.