Little seems to be known right now:

At least seven people have been killed after at least one gunman attacked a Sikh temple on the south side of Milwaukee on Sunday morning, police said.

Reports of multiple shooters have not been confirmed. Police say they shot and killed a gunman and that an officer had been shot several times in return; the officer, a 20-year veteran, was expected to live.

The Milwaukee Journal-Sentinel reports that police have no found evidence of a second shooter, yet continue to ask media not to broadcast images of their tactical units at the scene. A federal law enforcement official told the Los Angeles Times earlier Sunday morning that police were originally looking for two white shooters with large builds.

Speculation is pointless right now.