Discuss as:

2 nurses held in dozens of patient deaths in Uruguay

Matilde Campodonico / AP

The deaths of patients at this hospital in Montevideo, Uruguay, is part of the investigation that led to two arrests.

Two hospital nurses in the capital of Uruguay have been arrested as police investigate allegations that they killed dozens of patients, possibly up to 200, over several years at two hospitals.

Officials suspect that patients, all of whom were in critical condition, were given some sort of poison brought in from neighboring Brazil,  police inspector Jose Luis Roldan said Sunday.

Most of the victims were not terminally ill and their deaths were "unexpected," judicial sources told the newspaper El Pais in Montevideo.

The suspects reportedly cited "humanitarian reasons" for their actions but officials believe they killed patients who "demanded too much attention," the sources added.

The arrests followed a two-month investigation triggered by an anonymous tip, El Pais reported, adding that the two nurses appeared to have worked separately and barely knew each other.

More from msnbc.com and NBC News: