Authorities,
who
had
been
trying
to
piece
together
the
cause
of
the
explosion
last
Wednesday
which
injured
over
120,
have
ruled
that
a
methane
gas
leak
was
to
blame.
Pemex
said
that
it
has
not
detected
any
new
evidence
of
gas
on
the
campus
and
that
workers
can
return
to
the
buildings
that
house
most
of
its
senior
management
in
the
executive
tower
and
the
skyscrapers
A,
C
and
D
starting
from
Wednesday.
Pemex
added,
however,
that
two
buildings
-
B1
and
B2
-
will
remain
closed.
The
explosion
ripped
through
three
of
the
bottom
floors
of
Pemex’s
headquarters
in…