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Immigration and Customs Enforcement officers were gearing up to arrest at least 8,400 non-citizens in a massive September 2017 raid. They had a target list in hand. And for the most part, they were pumped.

“Happy hunting!” it said in one internal email asking for volunteers willing to build target lists for so-called Operation Mega.

That’s according to a pile of documents released Wednesday by activist groups including Mijente, Just Futures Law, and Detention Watch Network through a Freedom of Information Act request concerning Operation Mega — the largest planned operation in ICE’s history.

The internal emails detail how ICE compiled target lists of immigrants from data available through companies like Palantir, sent those lists to individual field offices, and set expectations for lofty arrest numbers. (An ICE spokesperson told the Intercept the agency doesn’t set quotas, although quotas are clearly outlined for individual field offices in the released emails.) The documents also show how ICE agents were more than willing to get involved.

For example, when the raid’s name was changed to “EPIC” in late August, one internal email shows a respondent joking that “it’s gonna be EPIC!” Agents volunteered to pitch in, according to the emails, and ICE’s San Antonio deputy field officer warned they didn’t “want anyone to feel left out” but wanted to “ensure we conduct the op properly.”

The raid was later canceled due to an onslaught of media attention and Hurricanes Harvey and Irma. However, the documents offer some detail on the immense planning that goes into a massive raid, at a critical time when advocates and lawyers are figuring out how to best protect undocumented immigrants from the next targeted sweep. Late last month, President Donald Trump postponed an operation set to target 2,000 asylum-seeking families and gave Congress a few weeks to figure out asylum reform.

“Probably won’t happen, but worth a try,” Trump wrote on Twitter on June 23. “Two weeks and big Deportation begins!”

Since Congress hasn’t come to a solution on asylum reform, raids could begin as soon as this weekend.

The so-called internal enforcement action, targeting families who’ve received final removal orders after missing court hearings, comes as the Trump administration is struggling to handle a record number of migrant families crossing the southern border.