4/9 8:32 AM PT -- Eric just tweeted about the incident, stating, "We are all safe. Thank you for your concern."

He finished by saying, "You don't know how much you're loved till times like these" and then quoted himself from his old "Monty Python" days -- "Always Look on the Bright Side of life..."

4/9 5:41 AM PT -- According to LAFD, the investigation found that "there was no hazard" and two people were taken to a hospital only as a precaution.

An employee of comedian Eric Idle called 911 after opening a letter containing a suspicious white powder ... triggering a heavy police and fire response to Idle's Hollywood Hills home.

Law enforcement sources tell TMZ the employee discovered the powder while opening a certified letter shortly after 6:30 PM Monday night. LAPD, fire and hazmat units were quick to the scene ... it is not believed that Idle was home during the incident.

At this time, it's unclear exactly what the powder inside the letter is, units are still on scene investigating.

Idle's career has stretched over the span of several decades ... including being a member of the British comedy group "Monty Python" and being the author of the Broadway musical "Spamalot."

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